Hello @Tomm
Nevertheless I just can’t understand whether there’s a tool for selective actions, like adobe’s brush.
Unfortunately, there is not anything like that right now.
Since you are alredy familiar with RawTherapee, maybe, you can be interested in trying ART, which is an open source “fork” of RawTherapee, created by Alberto Griggio.
With ART [1] you basically get this feature you are looking for (there is even a “clone tool” implemented, which is not available in RawTherapee, in case you are interested…)
BTW, with RawTherapee, in some future versions, you are going to take advantage of this feature as well [2].
At present, it is still in the works which is the reason you didn’t find it 
[1] ART feature requests and discussion]
[2] Local Lab build