She is 500 years out of date when she wakes up in Xenoblade 2.
True, but you can be even 1000 years out of date and still have a character not be overly ditzy about it. In this case, it's how her character is written. I.E. waifu bait.
I've seen plenty of other characters come out of it or time travel and be just fine even if they know nothing about the time period they are in. These are normally smarter characters that take more time to observe their immediate surroundings and able to not look like a fool in front of their new friends.
Note i'm not really complaining about her in general. I'm all about that waifu games. Just saying she's about as Ditzy blonde as you can get. IMO she'd still be ditzy even without the time gap.