The problem would be, you wouldn't even know until Krakourt or stealthy Acid Tanks attack.Well ,You do that , and i'll bring a shaitan with 2 overloads 2 manticore and a banshee , who do you think will win ?
or maybe an Iron Fist + Immolator and Black Lotus.
They are far more destructive and agile...
Also, GLA can always hit and run. (In case of your Tank Gen force) GLA can simply use mortar buggies running around your slow tanks while Acid eats your tanks like breakfast. And there are tactics to counter Iron Fist + Immolator (and even with Black Lotus) as GLA. In direct assault, China force is more destructive for sure. But in covert warfare, GLA is the master. You will never be able to use GLA force effectively if you put them to head-on assault like China force. You will never be able to make China force sneaky enough. If you use incorrect strategy, then it's very hard to win.
Well ,for the "sneaky" Krakourt , you just spread around listening posts then you get your "eyes" on the slow Monmouth n its friends and concentrate your def. forces there + black lotus to assist. For the mortar Buggy's, simple solution overloads with long cannons upgrade and couple of flame tanks and your set to kill.
and for taking down a Shaitan you know you need a massive amount of -GLA force-
And For the end of it...At rank 5 the game is plrobably close to an ending so the forces have to clash head to head sometime, and as you wrote china will win most of the time!
There for i thing lvl 5 gaming is not balanced . assault and poisen lack in capability !