Whats the purpose of a superior who doesn't have jurisdiction? To encourage the priest to keep the Faith and not go nutty, to provide the priest with holy oils (replaced yearly), to provide confirmations to the laity of the chapel the priest services.
"concrete actions/steps that would change if Fr Ringrose chose +Zendejas as a superior? " see above
1. I dont see why fr. Ringrose should have to sign over his chapel and $. Do all trad bishops require this? I've only heard of the sspx doing it.
2. I don’t know. I am not clergy.
3. See #2 above.
Ok, then according to your definitions, and because Trads live in a non-jurisdictional world, it is IMPOSSIBLE to say that Fr Ringrose (as an example) doesn't have a superior. And it is also impossible to know if ANY non-sspx priest has a superior, because your only qualifications are 1) encouragement, which is a private matter and 2) holy oils, which again, is not a public transfer or acceptance. 3) confirmations can only happen every 3-4 years for small chapels, so this isn't a good test either.
Bottomline: There are plenty of "independent" priests who have chapels where +Williamson and +Zendejas have visited, provided confirmations and (privately) provided holy oils. Thus, your original statement regarding the need for "independent" priests to have a superior, is (for lack of a better word) uneducated, because you have no proof that such priests even exist. Such priests can have superiors and you wouldn't even know, based on public actions.
So you should just keep quiet about the matter and quit judging priests.