What veterancy bonuses do Combat Engineers get?
v1 Unlocks the 'Trip Wire Flares' ability
v2 +20% accuracy, +62.5% repair rate
v3 No longer takes extra damage while repairing, +15% accuracy, -15% cooldown
So pretty horrible bonuses to pretty horrible weapon and squad in the first place.
Ost pios also get them, but they have stronger weapon and additional bonus of extra vision out of the gate, making them perfect re-crew unit, while recrewing with CEs is worse option and more expensive one then recrewing with conscripts or penals.
DLC faction engineer bonuses are all overpowering in comparison + the fact that they can use weapon racks and get additional men(obviously excluding sturmpios, but their veterancy is stronger then mainline inf vet).