I really get annoyed by too many unfinished things about CoH2, for example my PC can run BF1 on ultra without an issue with over 80 fps but in CoH2 my menu fps is 15fps and in game i dont get higher than 50 and when a explosion happens it even goes down to 40.
CoH2 optimization is pretty bad. Some of it is the lack of SLI support, some of it is just bad programming, and some of its memory leaks. Rule of thumb, restart every 3 games or so.
The maps feel like rushed, It seems like Relic did not take time to make a proper map for this game and you are forced to play 4v4 maps in 2v2 games. For example Ettelbruk station is one map that OKW is completely unbeatable in because of how large the map is and OKW can make a safe retreat point to the trucks and too many buildings which can be occupied by OKW infantry. In CoH2 grenades are effective against Buildings as soon as you throw the enemy goes out and comes back inside to avoid damage in less than a second but on other hand OKW has flame grenade by volks which completely disables the building for some time and you are forced to fight them in normal cover in super close quarter map.
CoH1 style building mechanics would actually work well here with a one-by-one reload mechanic. Unfortunately, that's not a thing, so we're stuck with Company of Buildings. I play a lot of 2v2 and its definitely worse than the 1v1 pool, there's too many maps that are too big, too small, chokepoint heavy or overly cluttered with buildings. Thankfully, there's a 2v2 map contest, so fingers crossed that some of the crappier maps are buried.
I take your advise about not using brens on tommies against OKW next time and go for 5 men squads. I usually only go 3 tommies + fast grenade upgrade and fight with normal rifles and in late game I take brens for vetted troops it always works and I always get full map control but suddenly the zero kill vet 5 units come back and I have to retreat. One retreat and entire map is in the hands of immortal vet 5 units of OKW.
Honestly, you could probably skip the grenades as well. Sappers, especially with 5 men, are a lot better at short range than you might expect, especially with the vet one cover bonus. They're also not bad as Bren gun carriers since their vet3 doesn't give them butter-fingers like Tommies and their weapons is (oddly) better than Tommy version. Vanguard and Special Weapons regiment can also really help with field control as Vanguard gives you a forward retreat and cheap commandos while Special Weapons gives you a halftrack.