If Tev could return to his original living form, would he? Why or why not?

No. Tev doesn’t dislike being undead. He’s also way more powerful than he was when he was alive. 

The Tevruden that died in the defense of Silvermoon and the Tevruden that was released from the Scourge at the end of the battle at Light’s Hope aren’t exactly the same person. They share (basically) the same body and a lot of the same memories but after being raised into undeath and nearly a decade of service to the Scourge, Tevruden doesn’t really see a reason to go back.