@MrF0x I can corroborate SaltyBird's reply since I check the translations. There was no tampering with dialogue, and it's written as it was originally conveyed, or as close as it could get.
Lesbian isn't explicitly said, but based on the reactions and her deciding on confessing to Sarah, how she is concerned about Yu wanting to still be friends with her after sharing this, and the utter relief she has when he says of course, there isn't any way to read it as just wanting to be close friends with Sarah instead of girlfriends.
As someone who is in the LGBT community, it is through and through a LGBT coming out confession. There is no confirmation on whether she is a lesbian or bisexual, however since we've only seen her romantically interested in a woman, I would say she's a lesbian until otherwise said.
Just let women love women, y'all
-LGG