5% mortars/indirect fire
10% HMGs
50% infantry
0% anything else
If i had to follow the same diagram for EFA engineers only (SP doesn't struggle vetting and USF/UKF can equip weapons, specially AT ones)
5% vehicles
10% mortars/indirect fire
50% HMGs
0% anything else including infantry
or alternative
5% vehicles
10% support weapons (not including AT guns)
0% anything else
You don't want to provide shared vet with infantry, cause then you offset the balance during the early game.
Engineers and support weapons go hand in hand. I don't think HMG provide enough vet on their own (due to how suppression mechanic works) and neither are indirect fire units able to provide enough vet early on to suddenly make vet 3 engineers.
The vehicle is purposely low due to them dealing high dmg against high value units.