There are some issues with the Reaper UI which are not related to the theme anyway. But I thought I would post them here for a reference.
I have Windows scaling set as 170%. I had to scale down these images to be able to upload here, so they might look a bit blurry.
JSFX GUI's are pretty messed up. The sliders are getting on top of each other.
Routing window has misaligned elements
VU meter scales are unreadable small
The project layer title is unreadable small
The monitor FX is unreadable small