Cellulose triacetate is preferred for camera film because it can be cement-spliced, unlike polyester. However, the easiest non-destructive way to distinguish the two supports is simply to hold the film roll up to the light and look through the flat side.
Polyester is quite translucent, whereas cellulose triacetate is rather opaque.
As regards the product said to prevent vinegar syndrome, without knowing its chemical composition, I fear its action may simply be to seal-in the evolving acetic acid for a period of time until it eventually bursts through.