I've taken a similar but slightly different tack in Stonehenge, in so much as I had tension between Blackthorn and the local Mercere due to Blackthorn arguably overreaching by trying to ban the training of Bloodcaps following a number of grisly murders. And then a Gifted Bloodcap child appearing at about the worst possible time in the debate.
So you've got Blackthorn being heavy handed but you can sort of see why someone saying "actually, training people with a lineage that inclines them towards violent murders is a bad plan" might mean well by it. You've also got the factor that the Mercere are a significant source of news, so members of Blackthorn were finding it very hard to build up a positive reputation in the Tribunal, and very easy to build up a negative one, which along with the fact that Blackthorn had been dominating the tribunal for a long time meant that a significant proportion of the tribunal didn't have a high opinion of Blackthorn. So Blackthorn had a good incentive to work directly with the PCs if they could.
I think I did later find something in canon that it didn't quite gel with - might have been a statement that Dhampirs were allowed as ungifted Redcaps in Translyvania, or implying that Tremere and Mercere usually get on well. I don't think it was a huge contradiction, though.
For Rome, I tend to head-canon it as having many of its covenants engaged in siphoning off vis from the rest of the Order (due to its scarcity there), often in competition with each other (it's 5e canon that it's fractious). So you've got covenants selling magic items, (Mercurian) ritual casting for hire, engaging in the book trades, mercenaries..Lots of trying to do-down the magi vying for the same bit of trade, with Magvillus and a large Tremere House Covenant that's getting fed vis from Translyvania trying to act as stabilising influences.
One thing that would be interesting to me in a new book is more about how the Hermetic services market (and Hermetic underground) work - there's a bit on the Mercere specific bits in HoH:TL, a bit on the book trade in Covenants, and info on Verditius prices in HoH:MC, but there's a lot of room for expansion still. Statted NPC magi who you can commission things from would be nice to have, at least for me (I suspect SG's might occasionally run into the problem of players arguing that they can absolutely have this thing because there's this NPC who will sell it).