This race is comparable in power to the Simic Hybrid race published in Guildmaster's Guide to Ravnica; probably underpowered
In some respects, I'm inclined to argue that it's a strictly weaker version of the Simic Hybrid, with caveats.
The main feature of the Simic Hybrid is that twice, once at level 1 and again at level 5, the hybrid is allowed to choose specific features to "augment" themselves with. There are 6 features in total that the hybrid is allowed to choose two of, but two of those choices are extremely similar to what you've listed here:
Manta Glide You have ray-like fins that you can use as wings to slow your fall or allow you to glide. When you fall and aren't incapacitated, you can subtract up to 100 feet from the fall when calculating falling damage, and you can move up to 2 feet horizontally for every 1 foot you descend.
Nimble Climber You have a climbing speed equal to your walking speed.
[...]
—Simic Hybrid, Guildmaster's Guide to Ravnica, pg. 20
So approximately, your race is equivalent to choosing Simic Hybrid but being locked into those two choices; but also gaining a [Finesse] Natural Weapon you may use instead of the Darkvision that Simic Hybrids get by default.
Even just in the context of the specific "slow fall" feature that your race gives, what you're offering is a little bit underpowered, given that the Manta Glide feature negates up to 100 feet of fall damage, whereas your feature only negates up to 60 feet; although your feature also allows for more horizontal movement per vertical movement.
The main potential benefit of your race is that it's extremely well suited for Rangers, Druids, and Monks, who otherwise would not be able to optimize both Dexterity AND Wisdom as a Simic Hybrid.
But even so, you could probably get away with buffing one or more of the features provided by this race. Maybe bump the walking/climbing speeds up to 30' and give the glide ability a longer range. Then you'll at least be on par with an official race.
Ability Score Increases
The ability scores seem moderately well-balanced, if a bit on the underwhelming side. Less powerful than those of a half-elf (+2 Charisma, +1 to two other abilities) and a little better than the variant human (+1 to two scores),the human gets a feat while Voidtouched gets access to some spells.
The ability scores are underwhelming because they don't synergize well. Although Triton's get a +1 to Strength, Constitution and Charisma. These synergize well together. A Paladins uses Strength for attacking, Constitution for HP, and Charisma for spell casting. As no class uses both Intelligence and Wisdom, you're effectively throwing away one skill and the two skills you utilize will be at a lower tier than everyone else(+1, +1 instead of +2, +1.)
Size
Should be the size of being before it was exposed to the Void.
Speed
Should be the speed of the of the being before it was exposed to the Void.
Darkvision
This darkvision has a radius of 120 feet, while most races have a radius of 60 feet. Should probably changed thusly.
Telepathy
This is very comparable to the Great Old One warlock's Awakened Mind feature. Awakened Mind requires that the recipient understand a language.
Memory of Madness
Resistance to psychic damage is very similar to Tieflings' fire resistance, but instead it covers a less common damage type.
Immunity to Modify Memory. This is fine. It's immunity to a single spell and makes sense based on the race.
Magic of Madness/Voidtouched Psionics
You have the ability to cast Mage Hand and make it invisible. The Arcane Trickster Rogue can do exactly this. I don't feel like this takes away from the Arcane Trickster, as the purpose appears to be telekinesis.
At 3rd Level you can cast Chaos Bolt once per short rest. Chaos bolt does 2d8+1d6 damage, with a with a 12.5% chance of bouncing to another target. The closest equivalent to this is the Tiefling's ability to cast Hellish Rebuke (2nd Level). This does 3d10 damage and can only be used as a reaction, not as an action. Chaos Bolt does. As stated by other people, this should be only be cast at first level.
While it's balanced, I don't feel like Chaos bolt fits in with the theme of the race.
At 5th level, you can cast Detect Thoughts once per long rest. The equivalent of this would be the Tiefling's ability to cast Darkness once per long rest. Both spells are 2nd level, though Darkness is more combat-oriented than Detect Thoughts.
Detect Thoughts is a much better fit than Chaos Bolt for this race.
Conclusion
I'm conflicted on the overall feel of the race. Structurally, it's very similar to Tiefling. Mechanically, I can see this being a very good race for interrogations, subterfuge, and reconnaissance. However, most if not all of the features in this race can be obtained as a warlock. The race kind of feels like a warlock; however, the ability scores wouldn't be good for a warlock. It also feels like a mystic, with the telepathic and telekinetic abilities.
There's no real unbalance to this race. However, I can't really figure out what this would be good for. I feel like it would be improved by adjusting the ability score bonuses (maybe retaining the bonuses of the creature of the creature's original race, and giving a penalty to wisdom to simulate insanity).
This is a very good start. It just needs some tweaking to improve the overall feel of the race.
Best Answer
This is not balanced with the other races in the PHB.
Assuming that these are two different sub races ...
Why this may matter:
Natural weapons at 1d6 + str ... significantly more than PHB races. (Though similar to Tabaxi from Volo's ... 1d4)
The base class benefits of climb, cold resistance, etc fit well enough on their own for the base race. You added a further two skills in the searching for perfection. (Equivalent to half elf skill boost).
Your Proposed bonuses:
For Eir: Dex +2. With two feats. Similar to vHuman.
For Hiojuth: Str and Con + 1. Similar to vHuman.
Compare to variant Human: +1 to two abilities and one feat, and one added skill.
Skills: Your "nimbles claws" as thieves tools is an equivalent to a vhuman added skill, but it isn't a skill. Using it as a bonus action begins to approach a feat. Add to that unarmored defense and you are out of balance.
Add Athletics Proficiency, which makes for three additional skills for the Hiojuth sub-race, isn't too far out of whack. You then added the half-orc racial unique ability for Hiojuth on top of that. And then unarmored defense ...
Natural armor as presented is equivalent to roughly plate armor with no shield: 10 + 6 + either Dex or Con mod. (Depends in how high your dexterity is at roll up, to which you have already added 2). If your starting Dex is 16, you have AC 19 without armor. A monk with Wis 16 and Dex 16 has a 16 AC. If you picked a monk, and you have a decent wisdom (14) and 16 dex (Eir), your unarmored AC is 20.
No, this is not balanced.
What to fix?
Size: Medium. Like all other races in PHB and Volo's. (Except for the small ones ...)
Base race: Good! But change Natural Weapons to 1d4 + bonus
Sub races: Lose the feats. Keep the rest.
Eir: Make nimble claws "equivalent to thieves tools" but drop the bonus action.
Unarmored AC: lose it, or trade one of the other base class attributes for a +3 bonus.
Notes.
The unarmored attribute is usually a class ability (Draconic Bloodline sorcerer, Barbarian, Monk, although a few monster races like Tortles or Lizardfolk have something like this).
An argument for "lose it" comes from @Ethan, who made a point in comments about how the game treats Armor Class, and bounded accuracy: the unarmored defense pushes up against a 5E design principle. There are almost no plain AC bonuses. Typically, the game presents an alternate calculation like similar to mage armor. "While not wearing armor, your AC is 12(or 13) + dex mod" would fit the design model more closely. (See the Sorcerer example in the PHB).