Use US phosphor and then the german fire ability and then let's speak about it. I can't see you know the real differences.
Edit: I am bored to make videos after video only so show simple diffrences.
The abilities serve similar but different purposes.
The Wehrmacht Mortar HT flame round is a way to force an AT gun or MG to reposition. You can fire the one flame round and then pull your mortar halftrack back to protect it and still force the enemy to relocate. It’s not a straight up killing ability, it’s a shoot and move utility ability that allows your mortar HT to reposition faster but still force enemy team weapons to move.
The USF WP rounds serve a slightly different role. They are intended to do big damage to an enemy team weapon so that other units can wipe them out in conjunction.
Both can use their abilities to deny an area to enemy units, such as a VP or resource point capture circle you are defending.
Are the abilities equal? No, but they serve the same utility in different ways. They don’t have to be 1:1 equal in order to be balanced.
This is why I suggest a slight cost reduction to the Wehrmacht mortar halftrack.