"Do you have a modern place?"
Translation:An bhfuil áit nua-aimseartha agat?
Technically, "you" is both the singular and the plural pronoun, depending on context. "y'all" and "you guys" are also acceptable plural versions of "you". But yeah, I totally agree. It would be nice if English had a distinctive plural "you".
You have to use the interrogative participle (an in the present tense) to turn it into a question, you can't just use tone of voice to indicate a question (though as all Irish speakers are bi-lingual, and will be used to that habit from English, you might get away with it in some circumstances, it would be a form of Béarlachas).
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No, it shouldn't. The 2nd person plural in modern standard English is "you", not "ye". Even the minority of people who say still say "ye" typically write "you". Duolingo will usually accept "ye" for people who want to translate agaibh or sibh etc as "ye" rather than "you", but not all exercises have been updated to do this.
As it happens, the default translation for this sentence uses the 2nd person singular agat anyway.