"The" healthy girls go to school needs to be accepted as well as "healthy girls go to school."
There is a report button, and it's preferrable that you report it and let the team take it from there rather than flooding the forums with useless posts like these. Please.
He's expressing the concerns that a lot of us have, which is by no means useless. What's useless is programming these to not accept the two obvious options and then being rude to people who point it out.
I hear the man on the audio saying "poo-ell-eye san-eye-ay in" Is there a reason the two instances of ae are pronounced differently?
IIRC from school, poo-ell-eye is correct and I would expect san-eye for the second word.
They are in the same case (indicating in Latin what job the noun is doing in the sentence) but only have the same ending if the adjective is formed in the same way as the noun, so it would be puellæ tristes/felices, the sad/happy girls go to school, feminine nominative plural like the noun but the adjectives tristis & felix are declined like 3rd declension nouns so the endings don't look the same. This can be bewildering at first but it eventually becomes second nature.