Let's say I use "gummy worms". Would a British reader be confused by reading it?
Yes. Few Americans would guess what you meant.And what if I use "jelly worms"? Would that be confusing to an American reader?
Y."Jelly Worms" in the UK. Both "eat" and "chew" work.
Note that "jelly" in the UK is "jell-o" in the USA. Not really. "Jell-O" is a brand name for a variety of gelatin desserts/snacks. "Jelly" in the USA is "jam" in the UK (totally different foods!) Also, in the U.S. jam has a different consistency (usually thicker than jelly) and made differently from jelly.
Let's say I use "gummy worms". Would a British reader be confused by reading it?