Hello! This looks really nice, but I'm using two 4k monitors. At 200% the text looks blurry, and at 100% everything's really tiny. I don't know if higher-res UI is on the cards, but if it is then this is my throwing my vote in for one!
Viewing post in Minimal Dark HD Aseprite Theme comments
Just to add more info: what you need to edit is the theme.xml file and is under the <dimensions> and <font> tags. I guess you'd have to double or triple the values to make sure everything is visible in a 4k screen.
As for the icons you could try upscaling the image sheet.png by 3x or 4x using nearest neighbour as scale method. ^^
Good luck and if you end up managing to do something you like, please share with us, I'm sure there are people with similar setups that would be happy!