character traits are optional ideals, bonds, flaws, quirks traits. They've been separated from Backgrounds so you can customise the core backgrounds with more whimsical traits
Cool. I prefer the Personality (Ideal, Flaw, and Quirk) be separate from the Background.
The Personality of a character concept can be inspired by anything: an inspiration from a tv show or movie, a character background, a class, a race, a feat, or so on. Really anything. So while each character building section (ability scores generation, race, subrace, background, class, archetype, skill, or feat) could suggest a list of thematic personality traits, ultimately the player has to decide which traits are interesting according to the overall character concept.
I guess, the "character traits" here in Witchlight are Personality Traits that relate to being fey as a planar origin?
Witch and Light are Shadae-Kai
I suspected so!
Where one of them is heavy set, it seems to reflect that elves have much more diverse appearances in 5e than they did in earlier editions.
The elves are more human-like, tall or short, muscular or lean, masculine or feminine or androgynous, light complexion or dark complexion, and so on.
I feel all of this diversity is highly appropriate for many reasons, including both reallife folkbelief and modern sensibilities, as well as empowering player concept.