I am only a learner myself, but my guess is that it is because the Irish question uses "toradh" which means "a (single) fruit," but in English if you say "is there fruit in front of you," the amount is ambiguous.* There could be one single fruit, or a whole basket of fruit, since "fruit" can function as a plural without having to add "s." If asked to translate "is there fruit in front of you" from English to Irish my instinct would be to answer with "an bhfuil torthaí romhat."
*Or am I incorrect, since "is" is the 3rd person singular form of "to be."
"An" in this sentence is not the article "the", but rather a question marker. So the lack of a definite article "the" in the original is the (frustrating) reason this is flagged as an error in sentences like this.
"An bhfuil an toradh romhat?" = closer to " Is the fruit in front of you?".
I think your issue might be more with English than Irish. If we were talking about "a vegetable"/"vegetables" rather than "a fruit"/"fruit" would you even be asking the question?
The confusion doesn't really arise with most mass- or non-count nouns, like "bread" or "soup" or "meat", where both Irish and English use the singular and "a soup", "a bread" or "a meat" would only be considered reasonable in very specific technical circumstances. That's not the case with "a fruit" or "a vegetable" or "a sausage".
Ok, yes that makes sense. I'm not enough of a grammarian to fully untangle the subtly different kinds of nouns in English in my head but you're right it's not something I need to be overly concerned about to learn the Irish constructions. "fruit" is obviously somewhat wacky in English, and it's not like deftly saying things about fruit is the main point of this exercise. Thanks for the help.