Update: So, I've tried the following:
1. I deleted all files of the game, including the persistent file, re-downloaded and tried the same route only to have it crash at the same line of dialogue.
2. When that didn't work, I updated my graphics driver with the latest version I could find for it, and reloaded the game save point I had created just before the line where it crashes, but it still crashes in the same spot. So re-downloading and updating the graphics driver still don't work. I get the same crash on the same line of dialogue.
Again, I have not yet tried any other routes, this is happening on Damon's route. I don't know if choosing a different group for that chapter would result in a similar crash or not. And it's weird that the game worked perfectly for three and a half chapters, only to crash at that specific dialogue line, when there are no vfx or anything at play either.
Or - now that I've updated the graphics driver - should I try deleting all files of the game again (including the persistent file) and re-downloading a third time and seeing if it works now? I'm just wondering if maybe because it's the same persistent file that the game created before I updated the driver, if that could carry the error over, after the update? I didn't get any sort of error or corruption warning when I extracted the game from the archive, so I'm not sure that's what causes the crash, unless there's some file in there that is corrupted and WinRar just isn't warning me about it before extracting.
So I'm kind of stumped on what to do. Is there any way I could send you the log file with the crash data so you can take a look at it? I couldn't begin to understand what it says, even though I looked through it. Could there be some error in the Ren'py script that causes this crash, maybe one that wasn't there before the last update of the game? To be fair I haven't tried the game before this latest update, therefore I have no basis for comparison, so I'm just throwing out potential theories.