You will not be able to do it at the F&W kiosks.
It has gotten more difficult to convert CS credits to snack credits, but some resort food courts will still let you do it. It depends on the resort and the CM. You'll have to ask the cashier if it can be done and how many snacks per CS credit (it varies from 1, 2, or 3).
Consider it pixie dust because it does say that it is not allowed in the dining plan FAQs:
Q. Can Guests substitute a table-service or quick-service entitlement for a snack?
A. No, Guests may not substitute a table-service or quick-service entitlement for a snack.