I think it's somewhere in between.
She's been keeping this up for years, probably decades, and she couldn't do that if she
weren't genuinely upbeat and hyper and bouncy.
Compare and contrast to Nash ka'Sharren. Nash couldn't have kept up her Blue Lesbian Kirk persona if she weren't, well, Nash. There's a real Nash somewhere underneath the 'mask of command.' But the main difference is that the real Nash isn't the invincible, dauntless borderline-superheroic woman that she tries to present herself as. She's not a
different person behind the mask, just a less... extreme version of that person, more capable of feeling doubts and misgivings and fears, which she normally hides behind quips and dauntlessness when on the job. I tried to explore that a bit in
Dreams.
Likewise, I'm pretty sure Zara ka'Athnon
really is the woman she presents herself as, she's not just an utterly hollow facade of cheerfulness behind a personality more like, say, Adele Chatsworth's. Zara may have been consciously amping the cheery side of herself up to keep up morale as a captain, but she wasn't faking it.
Or at least, that's who she was before the encounter with
Excalibur. If you read through the personal log entries, you see that they start out as a sort of canned thing, like maybe the Andorian equivalent of
affirmations or something. As she gets further and further into her exile in the pocket universe, the 'affirmations' start looking more and more like she's trying to remind herself of things that under normal circumstances she'd rather forget.
If this didn't break her, and I hope it didn't, she'll gradually revert back to type.
