Why does it need buffs in the first place? It's used incredibly often even without the buff.
It has free smoke which makes it much more survivable than the USF AA HT, and it can come out significantly earlier.
Why do you want every single axis unit to get buffed to be significantly better than its allied counterpart?
The flak HT is already significantly better than the USF one due to it's smoke and scaling + insane damage output.
You said you dont play 1v1, so why do you speak about it?
The Flak HT doesn't really have much in the way of scaling because it can't stick around on the field once actual real AT hit's the field (you can't counter play smoke by just shooting through it). I don't want every single Axis unit buffed (although I guess it's par for the course for players like you to phrase every argument like that because le ebin fanboy meme) but Axis light vehicles right now are kinda bleh due to their very low survivability.
I'm not at all apposed to the USF AA HT getting enough HP to survive an extra AT gun shot, but right now the Flak Track is used because OKW isn't swimming in options early game. A Flak Track represents a huge investment yet can only survive as many AT gun shots as the Kubel Can.
EDIT: One way to make it more survivable would be a skirts upgrade you buy for munitions so if you want to make your Flaktrack more tough you need to not get shreks or use nades.