If that's a 4K TV then it's first being upscaled by the converter to 1080p and then by the TV to get it to 4K, so it's always going to look rather blurry.
Your pictures show that the Wii system menu uses some larger icons and fonts for things like the date and time, so of course that stuff will upscale better. But if you look at the text in most of the banners then you'll see that it's just as blurry as anything in USB Loader GX.
Could you try using the
sWiich theme? It's got simple clean looking icons, so in theory it should upscale better.
If my r1272 release randomly softlocks for you then yes, the tabbed version will also softlock as I haven't pushed my changes to GitHub yet.