Don’t think that works for words that don’t have a verb as a base, i.e. Krankenpflege works because Pflege is a Verb and can be conjugated to Krankenpflegende but Mechaniker:in doesn’t conjugate.

Also Geborgene means nothing even adjacent to being a Bürger. I’d personally would have guessed Bürgende but even that is a major stretch. You would either have to create an entirely new way to conjugate nouns or you have to use synonyms that can be conjugated that way. Both ways will be a huge change to how German is spoken