Flares are amazing but I rather see them copy paste from OKW version.
+ 1 I love using them to spot for AT Guns/Jacksons to snipe OKW Trucks. They are also handy in team games for spotting for teammates artillery strikes. I just wish they were cheaper.
Balance-wise I think OP's idea is solid enough but I don't think Relic would ever do it just to save face with their stated ideology about bought veteracy (even if Tiger Ace still exists )
I still like Rifle Company, Easy 8s and White Phosphorus are still as useful as ever. Not like its NKVD level bad where it obviously needs a buff.