Ost vs USF is fairly balanced. USF vs OKW is broken which is why OKW did so well against USF in GCS2. OKW early manpower advantage is significant with how much better sturmpioneers are than riflemen and RE. It puts USF on the backfoot immediately.
Something needs to be done about USF early game against OKW. Maybe put MG in beginning in place of mortar. .50 cal would not be good against Osteer early game but would be much better against OKW in beginning and stopping sturmpioneer abuse.
I would like to see mg in tier 1 instead of mortars
Not that I'm against it but making this change would trigger a chain reaction in the balance of the USF.
Without smoke being available in T0 this would more or less force the player to go the tier in which there is smoke, but then that would make the player predictable and vulnerable to another counter.
Specific scenario for example:
Ost player gets MG42s, USF players is forced to go LT for the Mortar in order to provide smoke for his riflemen and destroyed the garrisoned MG42s, Ost player reacts to this by getting 222s as someone else already mentioned, the USF player then falls behind because even with the .50 cal and AP rounds it doesn't provide the fast punch of the 57mm AT gun needed to reliably destroy said 222(s).
So case in point, the USF needs the mortar right now in order to be effect early game because of the mortar's smoke and anti-garrison capabilities, if let's say the REs are replaced by Assault Engineers with the flame upgrade which would handle the anti-garrison dilemma of the USF but there is still smoke left, if the rifles are given back their smoke then people will again mainly only go for rifles, unless of course the USF T0 is redesigned with 4 or 5 man Assault Engineers, Riflemen with smoke and let's say a WC51 to provide more options for the USF's start but then people would complain that they're mimicking the OKW in a way with their Volks, Sturms and Kubelwagen.
But I think that perhaps all T0 MGs should be removed as AEgion suggested as well so there is less of the early game MG lockdown problem which would make it so there would be less reliance on smoke and anti-garrison capabilities, this would in turn also benefit the UKF which rely on the UC WASP for anti-garrison capabilities against Ost MG42s and have no reliable smoke because of the static nature of the mortar pit not being able to reach certain places on the map which you might need smoke right on the second.
But then again maybe the Ost will suffer then even if the MG42 is replaced by the Grens in T0, I'm not sure of that but I know that Relic made this change with a purpose during the UKF Alpha because they saw that the Ost would then underperform.
Maybe giving them 5 men Grenadiers and Panzergrenadiers would solve the issue and would make them less reliant on the MG42s? No idea, I sadly didn't reach this phase of testing in my mod to say from experience.
All in all I believe there are several ways of tackling the issue, question is which way the devs think of and decide on, that's all.