I think that the best balance for the Jackson would be to revert it's HP buff, but give it a smoke screen and it's 200 dmg back. This way it will be a frail TD, but can strike hard and disappear.
I recommend playing as OKW. It's the easiest faction with the least downside. It's core infantry is cheap and effective. It's got the best mid to late game gameplay. It's tank are extremely good. PZ4 eats infantry and panther can push back any allied tank with eases. The best part that it's the most forgiving faction since most of the time you will be placed with good players, and if you mess up, they will likely pick up the slack. There's been timed when I've been afk and my team managed to take on the allies and even beat them. Especially in 4v4.
I found that the only way to fix this is to delete mods and also unsubscribe to them so that as you delete them, they dont reinstall the next time you boot. My PC was infested with them. I noticed that every time I booted COH2 it would take the main menu a good 3 minute too load properly and get rid of the menu lag that also plagues the game.