so what's the semantic difference between 'Teastaíonn úlla uathu' and 'Ta úlla uathu'? the translation doesn't seem to specify if one of them is 'need' vs 'want'
In some dialects, teastaigh can only be 'need'. And, as far as I'm aware, bí ó can't mean 'need'
Is there any reason "Tá úlla orthu" wouldn't work?
that's true - but I would've thought 'tá úlla de dhíth orthu' should've been accepted?
That would be acceptable, as would Tá gá acu le húlla ; be sure to use the Report a Problem button if an acceptable answer isn’t accepted.
I think that would mean "Apples are on them."
So the word prompt suggestions 'teastaíonn ... ó' but that construction was not accepted. What's the difference between ó and uathu here?
"ó mé" -> "uaim"
"ó tú" -> "uait"
"ó sé" -> "uaidh"
"ó sí" -> "uaithi"
"ó sinn" -> "uainn"
"ó sibh" -> "uaibh"
"ó said" -> "uathu"
These transitions aren't optional - "ó mé" or "ó said" are not valid, you must use "uaim" or "uathu"
So the other construction would be for something like "Teastaíonn úlla ó mna."?
Yes. If you're not using a pronoun, you use "ó" with the noun. But "ó" causes lenition for an indefinite noun, so it would be "teastaíonn úlla ó mhná".