There are two kinds of level II potions. Adding glowstone to a potion will give you a stronger version of that potion while adding redstone will give you a potion with the same properties but with an extended duration. Some potions like the night-vision potion and fire resistance potion get no benefit from glowstone.
As for the potion of invisibility, you can brew that potion by taking a potion of night-vision and adding a fermented spiders eye. Generally adding fermented eye to any potion gives its opposite, such as potion of swiftness to potion of slowness or potion of instant health to potion of harming.
Beacons can also provide a large number of buffs that can also be given by potions. The buffs shared between the two are strength, speed, jump boost, and regeneration. The only buffs exclusive to the beacon are haste which increases mining speed and resistance which reduces damage. The beacon require a lot of spare materials, has a limited range, and can only have one of the buffs at level II or one level I buff and regeneration.
Now I'm not a genius when it comes to command blocks so I can't tell you what is wrong but I remade your command and tested it in 1.9.2 (which worked) and by comparing my command and your command there is some differences.
/summon Villager ~ ~1 ~ {CustomName:"The First Wizard",CustomNameVisible:1,Profession:1,Career:1,CareerLevel:42,Offers:{Recipes:[{rewardExp:0b,maxUses:2147483647,uses:0,buy:{id:emerald,Count:1},sell:{id:potion,Count:1,tag:{display:{Name:"Super Potion"},CustomPotionEffects:[{Id:5,Amplifier:5,Duration:600}]}}}]},Attributes:[{Name:generic.movementSpeed,Base:0}],Invulnerable:1,PersistenceRequired:1,Silent:1}
The generator I made this with is
http://mcstacker.bimbimma.com/
It might be a bit confusing at first but it helps me make several of my commands. It even gives a description for all/most of the options it gives.
Hopes this helps!
Best Answer
Here is a list of all status effect IDs, the potions use the same IDs:
https://minecraft.gamepedia.com/Java_Edition_data_values#Status_effects (archive)
You can also take a potion out of the Creative inventory, throw it on the ground and execute the command
The chat output will tell you all NBT data of that potion, in case you don't know what tags you need or where to put them.