I'm not fully aware of what Requiem does, but as I understand it, it delevels a lot of the world and makes a lot of tweaks to combat and such... I just finished my own tweaked version of Dreadflopps install, which for gameplay revolves around MorrowLoot Ultimate, Complete Alchemy and Cooking Overhaul, Ordinator for perks, and Revenge of the Enemies / Combat Evolved, as well as Frostfall/INeed/Hunterborn/YouHunger. https://wiki.step-project.com/User:Dreadflopp/Dreadflopps_Modular_patches
It took some time to do, as well as some tweaking to refine it, but I now have a massive, incredible RPG setup that looks beautiful and runs like a dream.
For anyone interested I seem to have solved my problem - I had 'Multi-display/mixed-GPU acceleration' set to multi-display performance mode in NVIDIA control panel for some reason. Setting this to single-display performance mode seems to have eliminated my transparency issue.
baronaatista's post in Any combination of mods that make a setup close to or even better than Requiem? was marked as the answer