Might be your phone, I'm on Android as well and I'm not having any crashing. If you mean the issue where it indefinitely stays on a black screen then you need to close it, remove it from your recent apps, and try reopening (perhaps repeat it a few times too).
That's a known issue with Ren'py on Android, I believe. It's basically out of the dev's hands unless they choose to heavily restructure things, so best thing I can suggest is saving frequently, at the very least before you switch apps, close the app, or lock your phone.