the okw has leig 18 fire rounds & walking stuka vet 1 ability that also has fire
Clearly talking about heavy artillery. If you want to expand the scope, allies have loads more light/medium/heavy arty doctrinal / nondoctrinal options anyway generally (quality notwithstanding). okw and ostheer sharing one arty piece is pretty boring, having the same relevant vet only makes it more obvious.
Ill respond to the rest: LeFHs don't need variety. They already have different vet bonuses with the OKW getting vet 5 LefHs which fits the factions' intended designs.
Veterancy and statwise identical until the OKW version gets vet 4/5, which only unlocks a quite uninspired / bad ability- for all intents and purposes they're the same, nothing special about the OKW lefh that fits the faction particularly other than having two extra stars.
Don't see why people ever think variety is a bad thing, as long as it isn't confusing - more interesting sandbox of units /abilities always adds to the game, they don't have to be better/stronger. Its a pity the hummel or similar didn't make it into coh2, would've been a neat counterpart to priest/sexton and probably less annoying than LEFH anyway since it would have higher cost / shorter range.