Your situation can happen; a risk of that type of surgery, but not "normal" or "common." I would be seeking another opinion and concerned.
"A normal side effect of ACDF?" I think not. One can have problems swallowing after the surgery because the esophagus, etc are being manipulated/moved when they go through the front of the neck to get to the spine, but a "feeding tube".....not normal. In my honest opinion, it is the nick in the pharynx causing all your woes.