So, I ran into a bug. Er, well, not really a bug, more like the game functioning as intended to give a weird result.
So, I was fighting the orc boss to start off the chapter, and disregarded the use of the cheat fairy (Sana can give Kuma extra actions, I highly recommend taking advantage of this in that fight). Because of that, it was a close-fought battle, ending with only Kuma still up. I went through the after-battle cutscene, went to go to the 4th town... and immediately got a game over.
Luckily, I had saved after the battle, so I reloaded and tried to leave again, and again I was hit with a game over screen. I did a bit of thinking and realized that with Anon and Sana at 0 HP, when Kuma left the party all the members were downed. And so the game, following it's programming, goes: "Looks like your entire party is defeated, time for a game over".
Tested a bit just now, and found out that Anon gets healed to 1 HP when the party restructures to just him in Acts 1 and 2, and going back to town 3 with him at 0 also causes him to get healed to 1. So looks like that just needs to be put in into the transition to Act 4.
So yeah, not super game-breaking or anything, but it's something to be aware of.