They pretty much did face off in rondo and richter wins.
Exactly. Technically, Richter has already fought Gabriel (who, after all,
is Dracula), and defeated him.
In a way, it's yet another reason why the LoS and canon timelines shouldn't quite be mixed...
Although, there aren't any specific plot devices in the LoS saga that suggest that Richter
hadn't met Gabriel as Dracula. Even if the LoS continuity contradicts the plot of many older CV games, I've always considered that the lore LoS left untouched (such as Richter's confrontation) would remain valid in both timelines. Unless LoS was meant to be an
entirely blank slate?