What would "they are not my skirts" be?
Actually, your version is the best translation for the current sentence.
Here's the breakdown:
It's good, report it if it's not accepted.
Surely im stating the skirts are not mine,which means the same as they are not my skirts. Confusing or what?
Two semantically similar sentences that otherwise could be told apart syntactically. Literally speaking, this sentence means "They aren't my skirts".
acelea nu sunt fustele mele sau va rooog acelea nu sunt fustele mele