I read it in junior high and I'm certain it was written for an 11-15 audience. I remember the cover being pinkish/violet and may have had characters on it. If so, the characters don't take up much real estate. The cover looked like a drawing or painting, not photography.
I remember it being about a young girl who travels through space, or at least on an alien planet. She is accompanied by her younger sibling, I believe. I also remember there being sequels, which I never picked up.
The only vivid memory I have of the story is the girl trying trying to navigate a busy alien market. The aliens are described really well. There are other humans here and an older human man even helps her. I know this isn't super helpful but that's really all I remember.
I think the younger sibling might be her little sister. I have no idea how they ended up at the market or what they're doing, but yeah. I've tried Google and Goodreads and looked at a dozen lists. I can't find it anywhere.
There is also a problem of her not being able to understand what the aliens are saying because obviously they're not speaking English and she needs a portable translator or something like that.