Is the move to renpy going to make modding more viable for these games? For example, a mod for LWT where you recast the characters with different models?
Renpy is very easy to mod. Last time I tried though, I was unable to decrypt the rpyc files for LWT so I could actually see the renpy code in the rpy files. I'm not sure if they're using encryption or if I was just using the wrong version of unren but modding kind of requires you to have some info about the game to have something to hook into. I need to know variable names, event names, etc or I can't do anything.
I didn't spend that much time on it since we've only seen a 12/13 day preview so far. Not enough there to be worth modding yet but I would definitely be interested in modding the full version if someone else doesn't release a mod that does whatever I might want first. Unren was able to unpack the rpa archives fine so you can see all the images.
The other thing you really need if you want to do a really significant mod is you need to know what settings were used to create the characters in the game as well as what assets were used, both for the characters and for settings. Otherwise if I try to render my own scenes, my version of Tracy is not going to look like the Tracy in the base game. Same for the rest of the characters. You can guess which models were used and try to tweak them so they look similar but without exact settings you're probably not going to get it right unless they didn't customize the character at all and just used a particular asset at stock settings.