I reviewed the wiki's Special:ListGroupRights and indeed, you cannot give other people bureaucrat right, even though you are a bureaucrat of the wiki. Fandom Staff must've have changed the wiki's permissions and prevent bureaucrats promoting other bureaucrats. You can contact Fandom Staff to request the change in user rights so that you want bureaucrats to promote other bureaucrats.
Edit: By default in Fandom, once bureaucrats are promoted, they cannot be removed.If you wanted bureaucrats have the ability to remove other bureaucrat, again you can contact Fandom Staff, but I don't really think it would be that successful.