If you want to be literal about it, you wouldn't use dath in the Irish for "he has yellow on", because dath is a noun, and he isn't wearing "a colour", he's wearing "clothes" or "a hat" or "a shirt" that happen to be yellow (in colour). So the noun in your sentence would be would be éadaí or léine or hata, rather than dath.
But in everyday speech, if you were trying to say "he's wearing yellow", then tá sé ag caitheamh dath buí or tá sé ag caitheamh an datha bhuí, or even buí atá á chaitheamh aige for emphasis.
traduttore tradittore. ....Literal might be incorrect grammar wise
Sentences like these leave me so confused. I'm at this point right now in the lessons where it's so difficult,I'm just flipping out on it, it's unbelievably difficult. I mean really,who says sentences like that? Some of the sentences we
are given in this whole program or really stupid! Why not give us every day commentary of what you might ask in passing of what need be? I know, I realize you're doing it to drum it in the head for memory sake, it's all laid out very well, but make it be more realistic for a question to be asked ... ETC ... As in,.... everyday speak! Forget about the linguistics part of it for me,I'm just totally lost with that! I think I've really hit a wall here to this level. I love it and it's fun, but it sure is difficult. wow!!! Most of my problem for keeping the memory bank happening is I don't study enough of it.I only hit on it once in a while when I have the time and so there are long periods where I don't study and then other periods where I study a lot. But now that I've gotten to this point of where I'm at, it's bewildering!!! And for immigrants, they think English is hard? Maybe it harkens back to The druids thing of "gift of the gab" in ancient time!!Aye,Begorrah.......
I dare say, it is not the Irish troubling you, some translations violate English grammar rules. This shouldn't be, else, students who are not native English speakers are being taught faulty English in the process. I think translation must be loyal to content, not to form, not necessarily. I must add that even a good native speaker will start wondering if he has missed on something and the faulty translations are indeed correct. They are not. The intention to reflect the Irish structure is good, so long as the target language rules are observed. We do want to become better and better at our new languages, but not at the expense of our native or mother tongues.
I don't see "the" in tá dath buí air.
Before you argue that it could be "he has on a yellow colour", I'll just point out that an Irish speaker will interpret tá dath buí ar as "it's yellow" (or "it's yellow in colour" if you want to be more literal). ar simply isn't interpreted as "on" in this construction.
There are lots of situations where Irish uses a definite article and English doesn't, and there are some situations where English uses a definite article and Irish doesn't, so word-for-word translations aren't always a reliable guide, but in this case, it makes a difference.
Is dath buí é is a poor attempt at a literal translation of an English idiom - a béarlachas.
One of the problems with it as a translation is that "yellow" is an adjective in "it is yellow", and you don't use the copula when using an adjective to describe a noun. Of course, dath is a noun, but then it's obvious that Is dath buí é is actually saying that the thing you are describing is a colour - it's not a banana, or a canary or a submarine, it's a colour, and the colour happens to be buí.