In English we often say "candy" to refer to several pieces of candy. In that case, shouldn't "there is candy inside" be accepted?
Yes, I reported that.
Sure there is.
Candy in british english is sweets. That should also be accepted.
Might a native Hebrew speaker say
"יש ממתק בפנים"
when there are multiple pieces inside, the way an American might say "there is candy inside"?
Nope, you have to use the plural