I think this is a bit off topic but in any case:
Every faction can be munition starved and good players will always find useful ways to spend their munitions.
But for this argument let's take Ostheer munitions use as an example. Your first 60 munitions is a critical investment that will shape your early game. Do you go for an early teller mine that can be game changing if you face a light vehicle rush? By getting that you're most likely delaying your healing by a minute or two so the manpower bleed will be increased as a trade-off. How about instead of a teller or healing you go for early lmg's to get an advantage over allied infantry? How about a bunker to protect that critical flanking route that could make your frontline collapse if properly used by the enemy? How about S-mines to keep a flank of an MG42 safe?
These are important choices especially in the early game and your choice of munition sinks will have trade-offs to healing, infantry upgrades or sufficient mining ability.
For USF however your primary munition sink will be the weapon racks and the only question pretty much is how big of a bulk one can buy immediately. Your healing is not tied to munitions, the aggressive playstyle rarely requires fighting positions as a necessity and USF don't have decent mines. (Riflemen take ages to plant them and you rarely have the luxury of idling your mainline infantry on mining picnics and the RE mines seem to be a bit of a niche even though they can be decent) Also grenades are not too common and they are usually seen with doctrines that don't have any late game munition abilities.
Also there are ways to play around the lack of double equipping rifles like before mentioned use of .50 cal MG spam which will be better suited for offense compared to an MG42. Also the M15 and its rapid suppression will make it easier to maintain crowd control and rifles can do damage safely without taking much fire in return.
For USF lack of munitions will mean lowered firepower. For Ostheer it instead means sacrificing healing, squad upgrades, mines, bunkers or doctrine abilities and each of these trades or bad investments can be extremely costly.
I don't really understand you point of comparison, USF early choice is based on fuel: ambu or T1 or T2 or rack unlock, not on munition. You can't really compare Ostheer and USF on this point.
On topic: if we agree that Ostheer mortar is OP, then yes USF HT mortar and Ostheer HT mortar are OP as well. The problem here with the USF HT mortar is about a pure cheese strategy and counter cheese knowledge, if you don't know how to counter it, you'll be in trouble be if you do, that's basically a waste of fuel for the USF player.
Now let's be honest. What strategy is the most popular for Ostheer players on teamgame, I can see two and one rely on heavy usage of HMG42s and Mortars, especially when facing dual USF. When as USF I see two HMG42 and two Mortar for each Ostheer players, well I'm sorry but I push my Infantry commander button and call 2 mortar HTs to counter this shit. What do you think I'm suppose to do since RM don't have smoke anymore? Call an outranged mortar of my own only to deal smoke a one location when I need at least 3 smoke to be able to do something? And on the mean time I try to flank I lost 50% of my squads by lucky random Gw34 mortar hits? Or maybe build 3 RE squad that can't do shit without an weapon, weapon I can't buy if I spend my munition on smoke...
I didn't watch your replay but I could post my last 2vs2 game USF/USF vs Ostheer/Ostheer, an ugly mortar spam game yes it was, but without those half-track that would have been a one-side match.
Now you want to know how to counter USF HT mortar, it is easy build less mortar of your own and more... 222. 222 counter USF HT mortars like hell, build 2 or 3 and rush them with a sweeper close enough to detect mines. 2 or 3 HT mortars also mean less infantry on the field and one or two HMG.50 aren't going to stop you.
You have to be realistic, the problem is definitively not the USF mortar HT but
mortars, all of them.