While I disagree with the implication (that you cannot successfully write a character unless you are yourself their mirror)…
Then it’s a good thing I didn’t imply that.
I have doubts about a MAN writing a LESBIAN. I would have almost no doubts about a lesbian writing a straight man because stories about straight men – their lives, their experiences, their sexuality, their relationship with other men nd women – are ubiquitous. Inescapable, even. Their perspective is the default.
Alternatively, lesbians stories – our lives, our experiences, our sexuality, our relationship with other women and men – are not readily accessible.
… if it helps, I didn't attempt to write her to be an example of what a lesbian character should or should not be.
No, it doesn’t. It’s the exact opposite of what would be helpful to say.
I wrote her to be Sera, and she happens to be a lesbian. I tried to take the same approach with Aveline. I didn't write her to be a strong woman, I wrote her to be a strong character. That she was a woman was part of her character, but not what wholly defined her.
Like Aveline, Sera has her flaws. I expect some will like her, and some will hate her, and that's expected. Hopefully because of her opinions/actions and not due to an expectation of what she should or should not represent.
If an American writes a Chinese person and decides they’re not going to bother learning about what it means to be Chinese, that they’re going to write ‘just a person,’ then they’ll end up writing an American.
Straight, white men get to be generic people. Lesbians don’t.
Straight, white women get to have generic ‘womanhood.’ Lesbians don’t.
I expect I’ll like Sera. I expect she’ll be a great character. But I would really, really like a great
lesbian character, and response like yours make me think you see being a lesbian as something that isn’t meaningful.
That it’s one tiny character trait among many, no different than having freckles, a bad haircut, or being impulsive. It’s not.
But I can't control that, so we'll see how it goes. I've had my hits and misses before. Fun every time. 
I appreciate you trying.