How does 'a pair' make it into that sentence and is there even a way of saying 'a pair of'?
For this particular phrase, 'pair' is a weirdness of English. Briste is a singular piece of clothing; one would have to research English to know why in English that is called a pair of something.
https://www.britannica.com/story/why-do-we-say-a-pair-of-pants Hope this helps
This is why I feel it should not have been suggested by Duolingo as "...a pair of trousers."
"She wears trousers."
I suppose it has to do with there being two legs.
In fashion, the piece of clothing is often called "a pant".
What's the difference, if any, between "brístí" and "bríste"?
bríste is used for one pair of pants, brístí is for multiple.
Why is "She is wearing trousers" wrong? What am I missing? :)
That is a different tense, and would be translated differently in Irish: "Tá sí ag caitheamh bríste". This is covered in later lessons using the "Verbal Noun".
Why didn't it accept "she wears a pair of pants."?
What's the difference between "she wears a pair of pants" and "she wears a pair of trousers"? Are pants and trousers different in Ireland?
"Pants" is usually considered short for "underpants" in Ireland, though it will be recognized as meaning "trousers" in certain contexts, in part due to the influence of US TV programmes.
A different sentiment than Caitheann si an briste
WHY CAN'T IT BE SHE IS WEREING TROUSERS!!!!!!!!!!!!!!!!
That would be: Tá sí ag caitheamh bríste
Irish distinguishes the two forms as English does. (Also, it would be "wearing" not "wereing", which latter isn't a word in English.)
Talk about inconsistent! So now bríste is trousers rather than pants