Actually in the Rhine Tribunal supplement only a minority wear Latin names, especially Bonisagus and most of the Tremere.
I thought there is a rule I missed.
There isn't a rule here. In the house book I think they tend to have Greek names, because Greek is the language of civilization where they are.
Actually, Criamon magi have a convoluted thing where those who see the house as waiting for a messianic figure have names from Greek tragedies, while those who don't deliberately chose non-pretentious names. That's why there was a Primus named "Jane". Well, that an that I was listening to a BNL albumn while typing which gave me the idea. "Cowards stay: traitors run".
Jerbitons are often named for saints, but there are a heap of young apprentices named or to be named "Constantine" or "Constanta".
Bjornaer tend to be named after animals which must get very confusing: How many Lupus can you have in a room before you need second names?
There were only a few names in that book all seemed to be Latin.
Nope. It is true some of the Tremere tribunal is in orthodox territory but the most of the tribunal including Coeris lies in Catholic ergo Latin area.
I explained this in detail here: 2nd <-> 5th edition combat differences?
This is probably just a difference in author preferences and inspiration.
HoH:S says that House Tytalus has a naming convention - they like to choose the name of titans, or names that sound like the names of titans. The primus has to approve a name as well, although this is a formality; so such names are not obligatory, just common.