I don't mind your weapon firing "energy" projectiles. It's WR universe, we got all the space magic we want with homing bullets, flying robots with unattached wings, unpenetrable forcefields, even energy shields would be a pain to justify in our world. So no problem with that.
My problem is the denomination : "railgun" is commonly used to refer to a kinetic cannon working with an electromagnetic burst in order to fire the projectile. Or, reading again your description after talking about energy projectiles, I had this reaction because of one single thing. In my head, seeing "heavy railgun" settled the thing : it's a big magnetic cannon. But in fact its an energy launcher which has certainly little to do with an actual Railgun. If you want to confuse people, stay like that for sure, but it's maybe not what you want