Eh, I find her with darker skin prettier. Looks good on her, plus it's the one she had naturally...
It sort of made sense why the light spirit would make it go brighter, since the dark one makes it darker, but still... Since she had the dark spirit first, it only makes sense for it to stay darker!
And yeah, I haven't read the novel but the way you present it can really change how one views what happened. I'd say both her keeping her cute darker skin, or turning it into an also cute light skin, makes sense plotwise... and I quite like that they kept it darker since she looks a lot cuter with it, it suits her and make her more eye catching!
What was lost with her keeping the darker skin tone(people superficially liking her now) is still there with the blessings thing, so nothing was lost plotwise tho, keeping her like she is is an absolute win in my book. ABSOLUTE. WIN. O3O