Nope, never fought a strong seleucid empire in vanilla. That is an oxymoron, no such thing exists.

In Mundus, well, it's much harder not to have a strong Seleucid empire since I've modded down the egyptian chariot stats and desert cavalry, and elephant stats in general. And, well, they don't have to conquer much of the east, they own it. So nope, never. Did I mention as the Germans in Mundus, I took down all their elephant resource cities first thing? They never bothered me much after that, even though they DID have 5 full stacks in Asia Minor alone.