To put it simply: No, “hai mangiano” does not make sense—neither in standard Italian nor in the Sicilian language. It is a grammatical mismatch.
Here is why it doesn’t work and what you should say instead:
The Grammatical Issue
The phrase attempts to combine two different verb forms that don’t belong together:
- Hai: “You have” (2nd person singular).
- Mangiano: “They eat” (3rd person plural).
In any Romance language, you can’t have a “you” subject followed by a “they” verb. It sounds like saying “You they eat” in English.
