The string is in english "%s not defined", which is gender insensitive, but in italian (and problably in other languages) "not defined" must be concorded with the argument.

I see that in the keywords list a "parola chiave non definito" (masculine adjective) is shown, while it should be "parola chiave non definita" (femenine adjective).

It's possible that the same argument translates to a masculine argument in some language and to a femenine one in others, so I think that this translatable string with argument should convert into many translatable strings without relying on argument substitution.