"The boy eats vegetables."
Translation:Itheann an buachaill glasraí.
I think a native speaker would understand your intended meaning as well as an English speaker would understand if you said "the boy vegetables eat" because there's only one sensible interpretations. But that doesn't mean your answer isn't wrong: you said "vegetables eat the boy". Word order is pretty rigid.
If I've understood the Tips and Notes on word order correctly, Irish generally follows the order 'Verb - Subject (does the verb) - Object (has the verb done to it, in this sentence). So "Itheann glasraí an buachaill" would mean "Vegetables eat the boy!" (Mind you, I wouldn't put it past some of the Brussels sprouts we get here to try!) :-)
I'm not exactly sure what you're asking, but I think yes.
Irish uses "Verb-Subject-Object". So the English "the boy (subject) eats (verb) veg (object)" goes to faux English "eats (verb) the boy (subject) veg (object)" or in Irish "itheann (verb) an buachaill (subject) glasraí (object)".
I think I see the problem: there are two common words spelt the same way: an
One of them is used to form questions in the present tense, and it eclipses the beginning of the following verb: an
n-ithann tú, an
dtuigeann tú, ...
The other is the definite article (the), and sometimes causes lenition, sometimes eclipsis, sometimes nothing. For the subject of the verb (like here), an lenites feminine nouns (an bhean) and adds a t- to masculine nouns that start with vowels (an t-úll). Since buachaill isn't feminine and doesn't start with a vowel, you should have just left it alone.
The preposition + definite article + noun construction is a whole different thing! If you want to say with the boy, you would say either leis an
mbuachaill or leis an
bhuachaill, depending on where you learnt your Irish. You can look up all the prepositions and see what they do to following nouns here
I hope that helps.