I don't see anyone else mentioning this, so I don't know if it's just me or what, but I just started playing the game (Mac 1.2 version), and sprites become naked almost immediately after appearing. And then, as soon as I click for the next message, their arms also disappear. Sometimes it happens to Emma too, but there isn't as much of a pattern to it. I have no idea what might be causing this or how I would go about fixing it… If it makes any difference, I'm on Ren'Py 8.3.3. (Should I be using an older version? A newer version?)
I've not heard of anyone else experiencing this with this game but this sort of behaviour is usually seen when there's a memory leak or related issues.
Personally, I'd advise running the game straight instead of through a specific version of Ren'py since it hasn't been tested on other versions and there may be incompatible changes as well. Shift+G can also be used to try using a different renderer and seeing if that helps.