When I work with an artist I make it very clear that it's OUR story, not just mine. I believe this makes a bond between the artist and the IP, as I want to make it so the artist actually enjoys working on our book.
Echavez is a very talented artist, although he mostly draws in the manga format, thus he gives some of the characters more anime-esque traits.
When I asked him why he made her hair pink, he just said he thought it was cute, while she may keep that hair color if I ever publish Idyll Haven in Asian countries, I believe her having brown hair is more appropriate in the west, as I envision the series having a hybrid style between western and oriental art styles.