Profile of Protos Angelus

Well, I agree that there should be a soft counter to doctrinal units in all non doctrinal ones. USF for example can't counter Axis arty without taking arty commander. I'm not sure about having a hard counter in non doctrinal. Trying to pull that off would totally destroy balance as you would need to introduce a whole lot more units and overhaul existing. Soft counters would be better at this stage. However, I doubt this will happen. Every faction has it's strengths and has units that have no hard counter non doctrinal. Units like that are walking stuka, Jackson (panthers are soft counters), werfer, Calliope, Elefant/Jagdtiger, Raketen (infantry is soft counter due to retreat)... just at the top of my head.

I wouldn't really go with smaller maps in 3v3. Maps like ettelbruck station really suffer from arty spam. 2 games ago I was playing vs 2x OKW and 1x OST and 2 of them went for arty commanders. Safe to say that our base was getting constantly shelled. 3v3 definitely needs to be played on more open, larger maps like Fields of W, Express Balls, and the like. Angermunde is an all around bad map with lots of close quarters and buildings (favoring early MG/sturm spam). There are a couple of badly designed maps that favor one play style in 3v3 and 4v4 but it's mostly good.

Will there ever be a change to the USF base design? The pathfinding is horrible within the base when choosing the upgrade or just plain leaving the HQ. Another thing is if you retreat 2 (or God forbid more) units that are in close vicinity of one another when the retreat has been pressed, they will reach the base and just clump up on one-another, getting stuck in a static retreat for 2-5 seconds. Also on smaller team maps, the Axis LeHF arty can reach the base and you can't really spread out your units to avoid wipes since it's dense and cluttered, and if you do spread out you can't reinforce since the radius is quite low. A simple quality of life change for USF by opening up the base more or complete overhaul.

If you're playing random teammates. There is not much you can do. AFKers, campers, newbie-like players (after 800+hours nonetheless)... etc.

Beyond that, what you said. Also, I'd like to add...flanking. Most of the games you will see people focus the mid VP while holding the closer ones with a bunker and maybe one unit. Use that. A lot of the map is undefended and unguarded. Use that to sneak one or 2 units to flank or one cheaper tank to take out anything it can. Works wonders in team games. Less viable in 2v2 since the maps are smaller and denser so somebody is bound to spot you.

You remove autofire from Pack Howi, you introduce even more microing (read howi doing nothing). USF is micro intensive already, that change would make it doubly so. I mean, God forbid if you press right click to attack even when AA HT is facing the enemy with it's gun (fun bug, it will just keep rotating, it wants to face front to attack but it can't so it will keep spinning and attacking when possible).
Only viable nerf to US howi would be to reduce any type of accuracy on autofire and reduce slightly barrage CD (nerf/buff). Any nerfs to it's damage or AOE would just kill it since it's only viable against static opponents. In most of my USF games I have never seen anyone not be able to deal with howits one way or another (or when playing against howits, never seen them as a "Oh no, he went for howits"). From my experience, werfer, stuka, LeFH arty are great counters. They can easily kill the whole squad on pack and force bleed. I mean, I once fired my pack howi from my base on Winnekendonk to defend vs a blod and 2 LeFH counterbaraged my base from their garden. People complaining about Ally OP but nobody addressing the Axis gardening potential in team games (Pak 88 + LeFH + MG bunkers + Elefant/JT). If by some chance you have no good offmap arty, axis can lock down a game just by spamming arty and parking heavies behind 2 VPs.
Another "balance" issue. The LeFH has high scatter, and it's a hidden gem on it. You're walking 2 of your rifleman or infantry or penals along your territory and you see some wild bombs dropping and so you move away and one drops outside of the "obvious" area and wipes both squads. 3 games ago I played against such an encamped team on Hill 400. We were winning 400-100 and had 60% of map in control. All of a sudden bombs started dropping on the mid VP. For 4 whole minutes we couldn't cap it. Either werfer, or stuka or some arty or planes. And if you try to push with tanks, 2 Paks have it covered. And infantry, 3 MG bunkers. Smart play by axis, had only MGs, pioneers and rest was encampment and we had 2 USF and 1 Soviet. Soviet went for Katyushas to try to break the garden but it was impossible. The Heavy cav on me and Mechanized on my US ally -> No arty. We lost 0-13. Every flank was either super mined or had MG bunkers. One elefant into that equation and it shuts down all Jacksons and SU85s. Every flank, coordinated attack was shut down by arty, MGs, 88s....

Maginot line has nothing on the encampment the axis can create.

1v1 and 2v2 is balanced. Well balanced I would say. 3v3 and 4v4 are seriously in axis favor if you do not snowball them early on.

EDIT: Seriously in axis favor if the draft is bad (2USF usually leads to a loss if the game goes late). Generally the balance in team games is slightly in axis favor if the draft is good for allies. Of course, that's concerning random teammates. I'm sure that pre-mades can make anyone yell "Unbalanced!!!! OP OP OP (or UP UP UP)"