OH this sounds hilarious.
If I was switched out with Juniper from the Chronicles of Oro right now, I'd probably be okay. I think my personality would clash with the Twins' just as much as Juniper's does (if not a tad more) and if I managed to hang onto her physical coordination in this swap, I might be okay with keeping up while running in the woods... I think I have as many advantages and disadvantages as Juniper, albeit they'd be different ones... The whole 'being them with my memories' thing sets this up for a really quick fix and good times in the story because... like, i know how the story goes? I could easily just drop helpful hints or 'hey guys this is a crazy idea, how about we do this instead of this' and pray to Ursa that they go along with it.
If I just was suddenly in Juniper's shoes as a 24 year old today... Oh boy. At first I would freak out and be the most annoying person on the planet, just frolicking around and being exited that it was all actually happening... and then as I settle down, I would realize that I would from then on be babysitting the biggest group of turds (... okay, not including Isa, Walter and Kanal) on an epic journey to 'just fix this crap already omg it's so simple you buttheads just open your eyes, geesh' as an all-knowing boss lady who's power only ends when government officials come into play. (Then I'd be screwed.)