Should squads gain XP for repairing?

This isn't a good idea.

-Sturmpios repair extremely fast already so they don't need it, plus okw has mech truck repairs too.

-USF have crew repairs which allow them to repair fast already. Also rear echelon perform well in combat with upgrades so they vet up fast too for the repair bonus.

-Brit engineers also perform well in combat which allows them to gain their repair bonuses faster. I believe their repair bonuses are also quite good in comparison to soviet engis and Ostheer pioneers. Brits also have anvil upgrade to allow fast repairs and many doctrines also have the crew repair ability.

The units that need some boost to their repair speed are Soviets and Ostheer. Most notably because their engis receive a large boost to repair rate only at vet 2 which is hard to obtain if you don't have flamers on both of those squads, who without flamers perform terribly in combat from the mid game onwards.

My suggestion would be to give Soviet and Ostheer engineers a repair boost if they decide to upgrade minesweepers that way they can be more useful since their combat capabilities will be reduced. This way you would have to choose for a squad that can perform well in combat with flamer, or a sweeper squad that can repair well despite not reaching vet 2 (with the rep bonus) very fast.

The problem is indirect.

But I will admit, I know I'm arguing a weak point here. Veterancy in CoH2 has needed an overhaul for a long time. If anything my argument only applies for infantry squads. For vehicles the current vet system more or less works, but for infantry, especially ones that wield AT weapons, it's a problem.

That said:

I think vet is far too ubiquitous which lowers the impact vet has (and can have, to be balanced.) But quite frankly, infantry vet was outright BROKEN for MONTHS and no one really noticed. (Or attempt to explain it without certain people shutting down all discussion for the sake of post count.) Units get to max vet almost independently of any strategy or tactics. In fact, just keeping a unit alive means that they'll most likely be maxed out in vet. But I'm mostly talking about the first few units built in the game, not Comets, Tigers or OKW units getting to vet 5.

I mean, I feel like units on the field could get veterancy automatically on fixed timed intervals and the vet system would play out more or less the same that it does now.

-EFA was outdated in comparison to both WFA/UKF.
-AT weapons should apply a debuff on xp gained (similar but on the opposite direction of the UKF commander), on the current system.
-People didn't notice that veterancy was broken is easily explained:
Not all aspects of veterancy were broken (at first). Abilities and defensive were proccing. Offensive buff were lost upon losing models but as the game progressed, DPS/lethality was increased on other ways through weapon upgrades and usage of AoE (grenade, mortar, tanks, arty).
-If you could recieve passive xp, you would just reward people who just sit with their units idle or camping.

I get that. But I also remember many people trying to investigate or discuss what they seemed to notice as a problem with vet.

I personally threw away a mod in frustration because I couldn't get my conscripts to reinforce with the PPSh upgrade I'd made for them. (Because it affected the entities that wouldn't be upgraded on reinforcement.)

People tried to discuss it but threads would get shut down or derailed by specific now-bant people who refused to consider that people thinking vet was broken were right. They'd go to lengths to show how the spreadsheet numbers 'proved' that vet wasn't broken.