Alright so in the process of digging into this I found a couple of other things, and for clarity sake I'm gonna explain a few changes I just made.
Firstly, because of the way the combat-end-scenes work, we can't really have a window of opportunity for you to use items after you've hit the victory or defeat button. The problem here is we need to re-run the victory scene function to regenerate the buttons according to the new stats that items may have given you, thus unlocking additional scenes. It would be nice if we could, but none of the victory scenes are really written and implemented with this in mind. I could have fixed it so that you could eat items and it wouldn't re-run the victory function, but that would have no real benefit to you, because we wouldn't be regenerating the buttons with their new enabled/disabled states based on those stats. The fact that it was possible thus far was an oversight that slipped through the cracks.
By looking into this though, I realised that as long as you haven't yet hit the Victory button, it's totally fine to let you chomp items, so I fiddled the means we use to limit this to explicitly allow it, rather than outright disabling it like we did in AS3. This means you can chug Condensol after combat has ended, providing you do it before you hit the Victory button.
Theoretically with some reviewing of a couple hundred victory scenes we could relax this restriction, but that would be pretty low priority right now.
This then also collided with a few other changes to get some targettable items properly working in combat, which made using Condensol potentially shove itself down the enemies throat instead of yours, so I cleaned that up a little more too.