Definitely saw Alien-a, sorry. But it bothers me more that the pronunciation isn’t very intuitive and I don’t think I would think to pronounce it the way you’d like people to say her name.
I see Alien-a, sorry.
Honestly I didn’t notice alien until it was pointed out, if she went by ally or lina or another nickname, at least at school, it would be fine.
Yep… alien+a… sorry. Bit unfortunate! 
I understand [name_f]Alyena[/name_f] would be better choice, but I really dig simplicity of [name_f]Aliena[/name_f] to my own language.
I really like [name_f]Alina[/name_f], but maybe I find it too short.
It’s a beautiful-sounding name, but sadly the “alien” part jumped out at me right away. I love previous commenters’ suggestions of [name_f]Aliana[/name_f], [name_f]Alyena[/name_f], and [name_f]Alina[/name_f]. I would also suggest Aliyena, which I think has the added benefit of helping clarify the pronunciation. Or maybe something like Olliena, with the option of adorable [name_u]Ollie[/name_u] as a nickname, would appeal?