Bulgarians have good options against archer civs like skirmishers, even if they lack the last defense upgrade they make a good spam unit, siege onager, siege ram, stirrups hussars/cavalier. Problem is they don’t have any eco bonus to get to those units. you won’t lose to an archer civ because you don’t have any counter but because you can’t get to it fast enough compared to an archer civ where you just need bracer, chemistry and arbalester to have a strong unit which doesnt cost a lot. bulgarians are just a very slow yet strong civ. If you can play an extensive feudal age where you can setup a good eco before going castle AND make a few kreposts to protect important spots, then you should be alright against any archer civ. Stirrups cavaliers are underated, they SHRED arbas.