At least that's my guess. I've had a hard time making the latter work in the first one, but only partially and only recently. To explain more thoroughly: the Shattered War starts without companion selection, and apparently something prevents them from gaining experience up until the first time you reach the party selection screen (as signaled by the creator of the mod, so I'm guessing it's a core issue beyond even his skill to solve). After that, you get back every xp and levels you have acquired retroactively. However, that's also the very moment when Dain's Fixes stops working. I never had any problem with it, it worked wonders in the base game and every official modules I played, so I'm positive it doesn't come from a bad installation of the mod.
Now the weird thing is, Dain's Fixes still work perfectly for my main character, they only fail to apply to the mod's companions, and only after accessing the party selection screen for the first time.
As I have extremely limited knowledge on these mods' inner workings, I'd very much appreciate any help anyone can give! \o I'll keep trying to find some way to fix this in the meantime.