Both medic turrets and the self repairing walls don't trigger on some attacks, mainly spitters from what i can tell.

Walls and repair turrets have a cooldown.
Also, the repair won't trigger if the target is too far away
This might be your case.
I agree that both of these mechanics are unreliable, but I'm not sure if it can be fixed at all

i understand. it would be very nice if u could maybe try to look into some "check for damaged" kind of trigger?
i guess it will be computationally heavy if even doable with the given api.
anyways, in this current state, it's almost impossible to upkeep the walls due to the lack of reliable repair.
thx for ur effort and time <3