It's odd that opacity is suddenly an issue for JoiPlay in a few different games... I wish I could suggest a fix, but I've also run into that issue in Goblin Girl Dungeon. My best suggestion is to save regularly and try to skip whatever triggers it. What I mean is when the event is happening, hold your finger on the screen to speed it up and it might skipped whatever triggers the crash. Helped me progress this game in a couple spots because the vfx caused some error in JoiPlay, but sometimes if I sped the game up it would skip the effect and wouldn't crash. It might take a couple tries, which is why I recommend saving frequently.