I think what follows is right, but please remember that I'm working from memories of about 15-17 years ago, so no guarantees!
I don't know whether you would call it resistance or what, but I seem to remember that something degrades energy attacks. It's been many years since I experimented with blasters in turn-based mode, but I'm pretty sure that they were doing less damage in some rounds than the minimum that they should — again with the IIRC caveat.
Regarding the "retreat" of the Terminators, there is knock-back from blaster impact, and as soon as the Terminator gets knocked back into the pack, another one gets in front of it, and there is what resembles Brownian Motion as the robots get in each others' ways. I agree it's not retreat as such, but that's how it works out.
Again from very old memory, if you take them on in real-time combat with blasters, dodging from side to side to avoid the robots' attacks, what happens is that a swirling tide of robots gradually gets closer and closer to your party, until you can no longer move far enough to get out of the path of the blasts. Shortly after that, the remaining members (because you'll have almost certainly lost one or two by now) of your party are toast.
I think all we differ on is the terminology.