"The woman and the man sing."
Translation:여자와 남자가 노래합니다.
The app is often very strict with direcr translations, including word order and grammar.
There is a difference between the two sentences: "The man and woman sing." (남자와 여자가 노래)
"The woman sings with the man." (여자가 남자와 노래)
In the first sentence, you have a compound subject (man and woman). In the second sentence, the subject is singular (just the woman).
Understand these subtle differences in meaning helps you become fluent so if that is a goal for you then, yes, the ordering of 와 and 가 is important.
For some reason, the 와/과 grammar doesn't follow that rule. It's the complete opposite, so if the noun ends in a vowel, it gets 와, and if it ends in a consonant, it gets 과.
I suspect it's just easier to pronounce that way. Usually when there are different variations of same morphological component, it's due to pronunciation.
I think it's also since "과" sounds similar to "가", if you were to use both after a vowel, it would be difficult to tell if you were using "and" or if you were using the subject particle. By pairing "과" with "이", and "와" with "가" (in terms of which sounds they go after), it becomes easier to differentiate the sounds.
You can use the report function to suggest missing translations. The tree is still in beta (I think), so they still have a lot of work to do.