My only gripes against this game thus far are the puzzles difficulty stems mostly from obscurity, and not from actual problem complexity. I ran around for quite awhile before I figured out that the little jars on the tables were interactable; and until I looked up the guide, I got stuck on the door riddle because I didn't find the 4 teensy points you could inspect on the giant bookshelves.
Maybe make the interactable items much larger than the non interactable ones? Or make the outline highlighting them significantly larger. Also, I would perhaps put the bowl you have to use to brew your potion onto the platform you stand on, then have the player brew it and place the bowl itself on the statue, or just have it float there on its own.
Apart from that, the clairvoyance type spell only reveals a single hidden clue. Having it reveal where the door is located isn't useful really. You have yourself a great in lore hint tool here, and I would suggest you use it as such. Like, maybe make it highlight interactable objects, put runes above the shelves you need to look at, that sort of thing. Stuff that might give the player a direction to investigate, instead of wandering aimlessly until they happen to mouse over an object while moving slowly.
The puzzle should be more about deciphering what the letters actually mean on the door, rather than searching for clickable things blindly.
