I'm surprised people keep getting stumped on the "Death of the Artist" achievement but I think it's because it's a lot less lenient than the other death-related achievements so I'll be sure to fix that in the post-jam update. The flower puzzles are also definitely the most reliant on outside knowledge which is why (save "Seven Human Souls", which I'm probably changing) they were the most straightforwardly named, Also one of the Final Zone ones is just wrong lmao.
I do think having a secondary hint system is a good idea since it moves the difficulty down a bit while keeping the spirit of the game, but I'm not 100% sure what shape that'll take just yet. Probably some kind of secondary text on the achievements once you hit 75%?
I'm also really glad you liked the final area since I threw it together on the last day of the jam and I felt it was a little jank in places, so I'm happy it actually turned out nice.
Thanks for the very in-depth review, and I'm glad you enjoyed the game despite getting stuck for a while!