If North Africa still has so many indigenous Christians, wouldn't they use either Punic or African Romance languages (probably both), as with the many Aramaic-speaking Christians in the Levant? And by extension, we'd know many of these cities by the names they held in Antiquity, or a later African Romance variation. That's a nitpick, I suppose. What I do know is that there's a giant list of titular sees in North Africa, and at least a few would be kept as actual sees instead of making new ones.
And what happens when as in OTL, an Italian state (like the Italo-Normans) conquers portions of North Africa? Malta's an obvious issue of what could happen, since we're ignoring butterflies by your scenario. And in the post-colonial era, why would Italians and Frenchmen join the North African church instead of local branches of their own church, especially when the local church's language is an African Romance language (I've always liked two major African Romance languages, one based on Carthage's African Romance and the other based on some city in Roman Mauretania, probably Caesarea in Mauretania or Tingis). That doesn't make sense. Even if they're treated a step above Arab Muslims by European colonialists, I can't see Europeans treating them as well as they would a colonist of theirs. So why would these Pied-Noirs join the local church instead of the French (why not Gallic?) Church's local branches.
I'm also skeptical of this Diocese of Benghazi (wouldn't the diocese be named for a Cyrenaican city more important than Benghazi in Late Antiquity?), since Cyrenaica was historically under the Eastern Empire, had strong ties to Egypt, and also an indigenous Cyrenaican Greek populace who wouldn't have adopted Western Christianity and instead would have been under the Greek Patriarchate of Alexandria.
- An African Romance language may well have survived until 1500, but it would be quite difficult to ensure its survival without some major POD as like European conquest at the time. More likely to follow the fate of Coptic- being used as liturgical language , but most of the local population adopting Arabic or Berber for the common day. But who knows, maybe Ceuta may retain its language.
- Italo -Normans did get hold of Tunisia, but unfortunately it lasted too short to make a change. Why would the colonists join the local church? Maybe it is by decision of the Pope who declares that North Africa belongs exclusively to the African Church. An exmaple among the Orthodox: the whole of Africa is under the jurisdiction of Alexandria. Or maybe at first there is a branch of the French church in Algeria, which then merges with the African church. Or its just decided that there be no overlapping jurisdictions because of reasons (Orthodox church decried ethnophyletism, when Bulgarians wanted to establish a bulgarian bishop for Constantinople. Smae might happen here.) Or maybe its just easier for practical reasons, as Carthage is closer than Paris.
- The Diocese of Benghazi is totally composed of Italian (and partially Maltese) parishioners.Yet there are also Coptic and Greek dioceses.
To sum up, ethnic composition of Catholic believers, more less. African denotes native Arabised African Romance population.
- Patriarchate of Carthage (80% African, 10% Italian, 10% French)
- Diocese of Laghwat (100% Pied-noir)
- Diocese of Capsa (Gafsa) (90% African, 10% Berber)
- Diocese of Sousse (100% African)
- Archdiocese of Alger (60% Pied-noir, 40% Berber of Kabylia)
- Diocese of Oran (95% Pied-noir,5% Berber)
- Diocese of Constantine (95% Pied-noir, 5% Berber)
- Diocese of Hippo (70% Pied-noir, 30% African)
- Archdiocese of Ceuta (60% Spanish, 40% African)
- Diocese of Melilla (100% Spanish)
- Archdiocese of Tanger (60% African, 40% Spanish,)
- Diocese of Rabat (60% French, Spanish or other European, 40% Berber)
- Archdiocese of Tripoli ( 55% Berber, 45% Italian or Maltese)
- Diocese of Misrata (40% Berber, 60% Italian or Maltese)
- Diocese of Benghazi defunct (used to be 100% Italian or Maltese) Most people left during Libyan civil war
- Archdiocese of Malta (100% Maltese)
- Diocese of Gozo (100% Maltese)
Ceuta, Melilla, Malta and Gozo. Oran and Gafsa have over 20% Catholic, and Tripoli over 10%.