But if it got rejected for not being finished in general (not concerning the endings) then what else is left to do? I thought it was all-but done? Is it voice-acting?
No; I clarified a lot of this on the Discord poll, but basically, while most of the
writing and voicework is done, as far as
actually getting it in the game, there's a good chunk left to do.
Once stuff's written, we can't just copy-paste it in the game 1:1 in like 10 seconds; I have to implement cutscenes, by hand, as well as camera movement stuff, sound effect placement, music placement, character expressions, etc. all myself.
Then, for game over cutscenes and a few other things, Frouge has to hard-code those in, since those can appear on any map (regular cutscenes are chained and load up on specific maps, which is why I can do them myself with the editor).
The dumb part is, if you tried to submit it with no voice-acting and then add that in a later patch, you probably could have done. (Disco Elysium did that, for example)
The difference is, we promised voice acting from the get-go, and the demo had it, too. Removing it wouldn't work, even if that was all that there was left to do.