I think everyone should be able to get adventurers as 1 civ in FFH can but probably from a UB U to each civ:
Bretonions a UB Stable (squires stable) and mounted adventurer that upgrades thru the knight path.
Sylvania/Lahmia a UB Graveyard (Graveyard library)and hedge wizard looking adventurer that upgrades thru the necro path. (possibly make Lichdom a necro III spell that requires hero promotion.)
Tomb Kings a UB Graveyard (great Tomb) and priest looking adventurer that upgrades thru the Lichpriest path.
I realy don't know much about the other armys but surely there is a UB and path for a adventurer in each civ.
Bretonions a UB Stable (squires stable) and mounted adventurer that upgrades thru the knight path.
Sylvania/Lahmia a UB Graveyard (Graveyard library)and hedge wizard looking adventurer that upgrades thru the necro path. (possibly make Lichdom a necro III spell that requires hero promotion.)
Tomb Kings a UB Graveyard (great Tomb) and priest looking adventurer that upgrades thru the Lichpriest path.
I realy don't know much about the other armys but surely there is a UB and path for a adventurer in each civ.