Hello @heckflosse
I have been following your improvements on github lately.
Together with Desmis’ NewLocallab dailies udpates, on his personal GIT branch, you really make me a happy Rawtherapee user 
Joking aside, by any chance, have you compared your latest work with the “similar” [1] sharpening improvements done on PhotoFlow?
I am not a developer and this is why I am asking this question. In short, I know nothing of algorithms and other technicals stuff…
BTW, lately, on YouTube, I have watched a video [2] showcasing your previous improvements on this same experimental tool. The comments on this video were extremely positive.
In addition, the sharpening results, available with the tools of Rawtherapee, were considered better than the results with Lightroom.
[1] Enhanced Unsharp Mask in PhotoFlow - please test! - #72 by Carmelo_DrRaw
[2] https://www.youtube.com/watch?v=Ak9xMYhkELk&t=9m35s