You do realise the lefh has a really short cooldown compared to ML20? It also fires 10 salvo's with no vet. The ML20 fires 10 with vet 1, and has no counter barrage ability.
Let's not make this "one howi is fine, the other is not", because they are both OP atm.
And that shorter cooldown justifies 47% less damage per shell?
Honestly, the LeFH will never be OP simply because of its low damage and lack of targets. Do Allies rely on static buildings? Not really.
The ML-20 will be pretty effective vs OKW. Against OST it's fine because Stuka Dive Bombs counter it.
Counter barrage is better than no vet 1 ability but that's it.
Honestly, both howitzers are overpriced and only one of those might be too effective against one faction.