Not sure on the mod thing, unless maybe you're mixing different mods? The SanchoMod for this game works fine, and gives you all the pointers you need to particular paths (so long as you pay attention to what it tells you when you get a choice to make!)
If you need a walkthrough though, you only need it up to the end of Chapter 4, as that's where the path gets locked in, and Chapter 5 only has 1-2 choices (path dependent) and they are not consequential really.
For the "harem" (MASH) path, there's plenty of posts recently showing how to get there, including this one below. You don't have to hit every single step, but if you do, you know you won't be missing any of the important ones.