I only speak of the main mod as that is the only one I have used due to the thread having a copy of the game that is modded out of the box, even if it is behind the actual game in development for valid reasons. I probably should have made that more clear. It makes sense that they didn't update to 0.48 and are waiting for something more worth the effort to come out since they would just have to do it again in the next version with Vren still messing around in the core elements that saves rely on. Maybe by the end of this year or next he'll be satisfied with those parts and he can start working on things that aren't pretty much guaranteed to break save compatibility. I think that might be the second biggest issue just behind the models looking as they do, which is by far the biggest issue players talk about.
I was just making the correction because you used the term all versions, modded or not.
I doubt the changes will stop so easily. They are a symptom of the game engine/ renpy being used.
Any time he adds a feature to the game that includes any sort of change to information stored in a character it will cause saves to not be compatible.
That can be something such as a new attribute to monitor or anything else that has to be stored.
Anything that has to be maintained such as status about a business or anything else can cause such changes.
The problem is he didn't really plan out his characters and so on very well before hand and make room for those potential changes down the road so it wouldn't cause issues.
One part of the problem is he way renpy stores stuff.
Generally, when I am making a game things are stored in an order and form that it doesn't matter if I add something in the game or software I am working on.
It would be more likely to cause issues if I removed something. Even then I would generally have my file loader simply remove the no longer useful data.
If they used something similar to a JSON file format they could write a system that wouldn't have issues loading from version to version. Any missing data could be generated and any extra data could be ignored and when it is saved again it would be corrected. I've used a number of formats to from binary types to txt version of xml and json.
The text version make trouble shooting a hell of a lot simpler at times.
You could still store a history even if you used a JSON format for roll back purposes.
The main mod could have been built in way the default game has a lot less of an impact on it.
That way they could focus on building the mod and less on trying to fit the game.
It isn't as if the main mod's save files are compatible with the base game. There is also no reason for them to worry about people uninstalling it. If they want to remove it delete the game folder and unzip the original over again. It's a lot less of a hassle.
Then when it comes to changes in the main game they can choose if they want to include it or not in the modded version.
It would be vastly less work for them doing it that way.