It seems count-productive for Duolingo to provide the correct answer capitalised. Makes things slightly easy.
My understanding is that this only happens in the apps — use the Web version to counter that counterproductivity.
It is an efficient way of introducing vocabulary.
every question in this lesson featured an eilifint and/or an lacha!
Yes, that used to happen to me a lot, too: One or two specific "topics" per session.
Would someone tell me how is Lacha pronounced
You can hear sample pronunciations from each of the 3 main dialects of Irish for many common words on the pronunciation database at teanglann.ie.