There's a small bug in the four-vertical-button device on the shelf: if you click some of the buttons, turn it off, and turn it back on, the buttons all display as autumn, but they click as if they were where you left them. (e.g., if you click the top button so that it shows "winter", and turn off the device and turn it back on, the top button displays "autumn", but clicking it changes it to "spring".)
I can't tell if that's causing weird behavior for the device in general, which I say because [further comments in ROT13] V'z qbja gb arfgvat qbyyf (naq gur xrl-yvxr guvat gung jnf va gurz) naq n fyrqtrunzzre. Gur qbyyf fher ybbx yvxr gurl'er qerffrq sbe, ynetrfg-gb-fznyyrfg, jvagre/fhzzre/jvagre/fcevat; ohg chggvat gubfr va (gbc gb obggbz) qbrfa'g jbex. (Abe obggbz gb gbc.) Juvpu yrnirf gur fyrqtrunzzre, juvpu V'ir gevrq gb hfr ba ebhtuyl rirel fvatyr qrivpr va gur tnzr fvapr V tbg vg...
Like Melphite, I got stuck on the fact that the cup was already full; I was looking for somewhere to fill it. (I then got very stuck on the next thing to do with the cup; the hint was there, but subtle.) It did take me a while to find the erq onyy, but I had in fact noticed gur pyhr va gur qenjvat; it just took me some time to work out what the right angle was.
Other than being stuck as noted above in ROT13, I've been very much enjoying this. The art is terrific and the puzzles are clever. I think my biggest issue, puzzle-wise, is that very early on I found (a) the seven-spoked button device on the table and (b) the thing indicating which buttons to press, and that made it really look like I had what I needed to solve that puzzle, but I was missing a piece of information. Since I didn't know that, I spent a lot of time pressing and re-pressing buttons, certain that it should be working.
At any rate, I hope to get unstuck soon on what really looks like it should be the last step here...!