The Engineers description states it repairs drillers you lose after combats you win. But i currently have a hostile sabatuer on its way that, due to a general, will destroy 10 drillers, then nothing. I have an engineef present at said base so why doesnt it repair lost drillers?

Unfortunately, drillers lost from generals, lieutenants, thieves, and kings are NOT included when the repair stage is taking place. They happen in the specialist stage, and the engineers effects only work on the driller stage. (I think I'm right here... Hope I'm not giving false info )

It just works for drilles that are lost by other drillers or shields .