Yes RT 5.9 is packaged for Tumbleweed.
But before I go and install that non flatpak version of it to my machine could you please explain what the correct behaviour of RT would be?
I guess it should first run exiv2 (from /usr/bin) override my lensID by the value of whatever I put 3 toy be equal to and then look in lensfun dir for a match? Thus the entries I mentioned in nikonmn_int.cpp do not matter?
Well I did go and install the packaged RT 5.9 (changed the ~/.config/RawTherapee-AppImage/options configuration file so it can also apply/retrieve lensfun info and the results came to be the same as the flatpak one.
Note that also the Geeqie (which is not related to lensfun info) behaves the same:
