From your link:
-Reduce spammability
Sure, but make them worth the increased cost in the first place. Increasing the cost because of DPS isn't one and the same though. Their piss poor accuracy against anything smaller than a heavy makes that somewhat redundant.
-Increase scatter on attack ground order
You shouldn't have to use the attack ground order in the first place. That's a roundabout solution to the issue.
-Reduce damage to bunkers. With high damage and firing behind shotblockers the weapon can be easily used to take out base bunkers with little time for reaction
Since when can static bunkers react to anything? lol. Not sure what you are trying to argue for there.
Point #1 seems like a decent enough suggestion. No issue there.
Point #2 is a bit iffy. That would be be bound to cause some odd occurrences, especially against infantry.
I do think that PIATs will see some sort of fix, though its unlikely to be anything like your suggestions.
Weapons with high scatter should not bypass their scatter with attack ground...(goes for a number of units)
Bunker can not react but piat can destroy them faster then someone can sent troops to protect them.
Piat damage vs infantry can be fixed the same way PTRS has with bonus damage vs vehicles as suggest in my suggestions...