Is this too ugly or even buggy?

Looking at gnus-tilde-cut-form, I found another bug, a "," is missing,
in gnus-tilde-max-form, too, try this:

   (gnus-tilde-max-form 'bla -3) or, more high-level
   "%~(cut-right 3)L" as gnus-summary-line-format

Not only does the following patch insert the ",", it also make the
functions more readable than they were in the last weeks (IMO). If you
don't trust them, please insert at least the two ",".