In acquiring CSs, I think Venice could have an upper lead with Serenissima because all Venice needs is the Great Merchant of Venice to puppet a CS while Austria with Diplomatic Marriage requires alliance with a CS, plus 5 turns of alliance and a merchant's fee of approximately 200-500 gold. Diplomatic Marriage probably lost its touch from Gnk in BNw because making gold required less production than it does in BNW since now a civilization needs active trade routes to make the much required gold that used to be made naturally in GNK to purchase the CSes. Venice on the other hand, only needs to make sure the merchant gets to the CS' borders and simply make the purchase.