[Paul M]

I understood your question - however, like I said, I do not know why it would say Lurker in the first place.

In your example ;

This user is silent for some time and moved in a usergroup "Lurkers", it is given the status "Lurker"

There is no code in the mod to set usertitles (the bit in red) so something else is doing that.

Obviously, there is no code to reverse something it isnt doing in the first place.