Kayfenok
Auto-translated
It weighs less because it doesn't include scenario maps. That's at least one reason. As for the bugs, we need to take a look. Right now, the fifth mission for Ilia is crashing on my game. Although it wasn't happening before. But I can install your mod from the link you provided and check it.
Added 3 minutes later
On your mod, that mission also crashes immediately after it starts.
That's strange. I just checked your version and the version with the smaller file size, and neither of them crashes in my case.