Whatever you're doing, Natural Waterfalls is probably an amazing addition. And come to think of it, Natural Waterfalls claims to have a water mod built in that I haven't tried out yet.
It's been a hot second since I modded Skyrim, but Realistic Water 2 was always my pick! I used several other Cathedral mods though (Landscapes and Weathers) – Cathedral Water not making cell edits is certainly an appealing feature too.