You do get a bit more tower knowledge if you complete the Adamant Vaults, which is clearly supposed to be the main reward from doing it, not the 6g.
But I agree the rewards could be a lot more for this, especially as it appears to be designed with the intention of being slightly harder than the normal wings of Torghast, but mostly because it took a 5 gem run to get to the Vaults. I also wish it lasted longer, takes long enough to get there and then because it’s only 2 floors its just over instantly. Boss fight could be a bit harder too imo.
To balance it out, and to just give some feedback on this wing, on the plus side I love the aesthetics, the fact they made some genuinely unique traps and dangerous machine-things, and that it feels a bit like a reward in and of itself as it took time to earn the access to this place from the tower knowledge needed and the 5-gem requirement.
One thing that can’t really be changed but that I’d question in future is their choice of naming. “Adamant” doesn’t appear to have any lore relevance to this place at all, if it does then its very unclear and not explained to the player. Adamant is supposed to be something similar to diamond in common fantasy worlds, its there in Runescape, its in Lord of the Rings. While it is there as Adamantite as an ore found in Outland, what does this have to do with the machine of death and the Jailer and Torghast? Bad choice of name.
What might make more sense is to call it something like these suggestions depending on the lore of the place, the Anima Vaults, Stygia Vaults, Soul Vaults, etc loads of much more sensible suggestions.