I'm also having this issue. Or well, sort of. Project ENB 0.113 + Climates of Tamriel makes the dungeons way too bright, even with the darker dungeon esp's. When I install the CoT plugin for hazardous or hardcore dungeons the darkness is "sufficient", but not as much as you'd expect from a hardcore darkness preset. The problem with this though is that it makes the image very washed out/hazy inside dungeons, like the ENB author describes.
I have tried swapping in Countervibe for Project ENB, but the result was exactly the same. Countervibe seems to be slightly darker from the get-go in interiors, though.