Hi,
(Disclaimer: I used deepl to translate to English, I hope it’s accurate…)
As @paulmatth wrote, you can use the brush mask in “add mode” to modify the other masks (including the colour similarity one). No need to copy anything from the clipboard, just switch to “add mode”. I’m on the phone now but if needed I can record a short video when I’m in front of my laptop.
The ability to print directly from Art with icc profile support, if no additional corrections are required after processing in Art.
This would be nice, but alas I don’t have a printer, so I can’t really work on this, sorry. I do print but I use online services for that (sometimes with mixed results, but that’s another story 
The latest version does not directly support hasselblad XD2 100, so you need to convert to dng to process the image.
Can you share a problematic raw file? Thanks!
I previously used rawtherappe and it seems that highlight recovery is more efficient (propagation by color).
Can you show an example? Indeed the colour propagation code in art is slightly different from that of RT, so if you have examples of regression I’m certainly interested in seeing them…
Best