You just answered your own question. Only 7 TF's went back to Cybertron at the end of Beast Wars. Optimus, Rhinox, Rattrap, Blackarachnia, Silverbolt, Cheetor on the Maximal side. With Megatron their prisoner. Also the motorcycle, Thurst, was Waspinator. The protohumans threw him out as their leader and he went back to Cybertron (and to his own time) somehow. Silverbolt was Jetstorm, the jet.