I wrote "leis a gcailín" because that's what I heard. We need to listen to their girl makes sense to me. Not accepted.
"We need to listen to their girl" is *Tá uainn éisteacht lena gcailín".
leis is either "with him/it", or it is the combination of le and a definite article - leis an or leis na, meaning "with the".
le + a -> lena.
Would “listen with the girl” also be an acceptable translation for éisteacht leis an gcailín?
Do you mean "to listen alongside", as in "I listen to the music with my girlfriend", meaning that we are both listening to it together?
Otherwise I'm not sure exactly what "to listen with" means in English.
Éistim leis an gceol i dteannta mo chailín
= (Literally) I listen with/to the music in/with my girlfriend's support
= I listen to the music with my girlfriend.
I don't think this translation is right. When you hover over the words it says that the "eisteacht" means "to listen" and that "leis an" means "with the", but not that "eisteacht leis an" means "to listen to the". I'm not an expert but maybe the shift should be included when you hover over the words to check their meanings.
I'm sure it is. I just think that if Duolingo is going to have the drop down that tells you what things mean while you're in a lesson, then it should have that one add to the list, since not everyone learns the same way and not everyone using Duolingo is multilingual or a polyglot, is all. It also doesn't explain why it's wrong, so it can be difficult to figure out what you're doing wrong in the lessons.