[RPG] Are these rulings for Command balanced

By comparison to the pre-existing Instruments of the Bards, the first is balanced, the second may be slightly too strong but is probably alright

Let's compare your proposed spell lists to the pre-existing sets from the Instruments of the Bards of equal rarity:

Mac-Fuirmidh Cittern (Uncommon):

barkskin, cure wounds, fog cloud.

Fochlucan Bandore (Uncommon):

entangle, faerie fire, shillelagh, speak with animals.

Doss Lute (Uncommon):

animal friendship, protection from energy (fire only), protection from poison.

Koeth Flute (Uncommon):

feather fall, gust of wind, protection from energy (cold only).

None of the pre-existing instruments have any damaging spells at all, which is good for your proposed instrument as it also has none.

We can assume that the two protection from energy spells are roughly equivalent, so let's look at feather fall and gust of wind.

The first is a situational spell, in fact, it can only be cast as a reaction anyways. I would say this spell is situationally useful similar to fog cloud, faerie fire, and protection from poison, and isn't particularly strong compared to completely ending a current poison.

The second is a somewhat useful spell as it allows you to push enemies and cost them some extra movement, but when compared to entangle which has a much stronger effect (restraining), it seems balanced. I would say that entangle and animal friendship are both good "shutdown" spells, as they deter or limit their target much like gust of wind.

Conclusion:

The proposed instrument, aligns well with the pre-existing instruments and follows the slight pattern there as well. If anything, I would say it is weaker than the others, though not by much as the usefulness of the situational spells is very campaign-specific.

Cli Lyre (Rare):

stone shape, wall of fire, wind wall.

Canaith Mandolin (Rare):

cure wounds (3rd level), dispel magic, protection from energy (lightning only).

Naeris Viol (Rare):

enemies abound, pyrotechnics, heroism, thunderstep.

We can immediately see that your instruments provides more spells than the others, though this is not exceptional as the Fochlucan Bandore mentioned earlier also did this.

Healing:

I feel a good comparison to make is between cure wounds and heroism. The first heals for 3d8+MOD while the second gives MOD temporary hit points each turn that concentration is maintained. Assuming a modifier of +4 it takes 5 turns (not too long for a combat) for heroism to become better, and with a modifier of +5 it takes only 4 turns. Thus, I feel alright saying this spells are about equal, if not having heroism being worse as it takes longer, is not guaranteed due to concentration, and cannot restore a creature to consciousness.

Damage:

Your instrument then has a good damaging spell (thunderstep), though it does an average of 16.5 damage compared to wall of fire's 22.5 damage. Though fire damage is often resisted, wall of fire will often hit more enemies as you can define its shape better, and it does not require enemies to be near the caster. While thunder step also allows you to teleport, and get out of a tight spot, wall of fire persists (barring concentration) and can deal damage multiple times, detering (shutting down) enemies as well. This puts them about on equal footing, if not with thunder step being worse.

Shutdown:

Your instrument then gives two "shutdown" spells: enemies abound, and pyrotechnics. These can either turn an enemy against its allies, or blind an entire group. Though these spells are not particularly strong, and I often see a caster picking up dispel magic as it is the spell to shutdown persisting spells, which are often quite strong themselves. The choice is whether you want to shutdown an enemy or shutdown a spell. These seem about equal to me, though dispel magic has some more use outside of combat, the two spells provide versatility simply by having more options.

A problem:

This would have us comparing thunder step with protection from energy, where thunder step is quite often the superior choice. This points out what I feel the Viol does too well; it covers too many bases. Your instrument provides healing, shutdown, and damage (with a bonus escape tied in). Though it isn't particularly great at any of the three things, it does provide a lot of versatility for the user.

The Lyre provides shutdown (the walls) and damage (wall of fire) but not any sort of healing, compared to the Mandolin which provides healing (cure wounds), and shutdown (dispel magic). Your instrument provides all three.

Other Benefits

Note that both of the other instrument also provide a situational benefit (stone shape and protection from energy), while yours, at best, provides heavy obscurement (pyrotechnics).

Conclusion

Your instrument doesn't excel in any of these categories, so it is likely balanced, in fact, it is outdone in each category by one of the other instruments. What may make it slightly overpowered is simply the amount of versatility it provides with its spells.

In this case, you're probably asking the wrong question.

The thing you're discussing here is a tool for the DM, designed to benefit NPCs. Its primary effect is going to be in adding PC-hostile terrain effects to encounters, probably mostly combat encounters. That means that "balanced" isn't a particularly meaningful question to ask. Instead, it's going to be a matter of adjusting encounter difficulty. You're listing prices, but the prices aren't really important unless the PCs manage to seize some and find a merchant willing to buy the stuff. After all, the smoke spreads from lit braziers. How often are the PCs going to be in an encounter where they have the time to set up a brazier and light it?

Instead, the question that you should mostly be asking is with respect to individual encounters, on whether the difficulty is in line with how hard you want the encounter to be, once the smoke clouds are taken into consideration. Even on the off chance that the party manages to briefly acquire the assistance of some Yuan-Ti and have an encounter where deploying this stuff would make sense, it's still a matter of balance for that specific encounter.

If you do intend this to be something that the party is buying and using, you have other issues.

First, you're talking about single-use alchemical items, some of which have price tags in excess of plate mail. 5e isn't designed for stuff like that. By the time you get enough money that buying some of this stuff would make sense for general use, you should already be on the magic item economy for your gear-based boosts.

Second, there's the fact that this is uniquely beneficial to Yuan-Ti. That makes the first issue much worse. If you have any yuan-ti in the party, then once the party becomes appropriately wealthy, they get significant benefits from being able to lay out raw cash, at a level when "lay out raw cash" isn't supposed to get you much of anything. Basically, this becomes a backdoor buff of the Yuan-Ti race, and the Yuan-Ti race is already one of the strongest PC races in the game.

Third, you need more info. Most of the time, the party gets into fights without warning. Sometimes they have time to prepare. For the first case, you need to know how hard it is to prep a brazier with one of these things, how fast it spreads once you have, how hard it is to disrupt once it's burning, and what happens if you just light the thing and chuck it on the ground. For the second case, you also need to know how long the smoke lasts once it's been produced.

In general, then, introducing this stuff as something that the party is expected to acquire and use in general is probably a mistake. Introducing it as a terrain feature to make certain fights more interesting is great. If you're doing the latter rather than the former, then "balance" is not the way to be thinking about it.

For your own usage, you might be well-advised to start small and work up with this stuff. Start by giving the party an encounter that should be a cakewalk, plus one cloud of ossra positioned such that it will be a meaningful benefit to the enemies. That will give the party a chance to encounter it (and realize what they're dealing with) and you a better idea of how much difficulty it's worth. Then work your way up the chain, both in using ossra and overall difficulty. That way, once you get to your particularly challenging climactic ossra-based encounter or encounters, you'll have a much better idea of how much difficulty they're actually worth (and your players will have a better idea of how to handle them).