I agree that this test is to take with a big pinch of salt. Especially that some people are on the verge of this and that, some people are categoric in the answers. Anyway, serves well for character building in stories, and in real life I guess for inspiration ?
As for Lydia's case, I am pretty sure she won't ever fit into the Diplomats or Explorers category ever. Might be a Commander (like Miranda Presley- aka Anna Wintour aka the lady who was fired of all her jobs untill she finally landed the chef of Vogue position, creating her own rules and bossing everyone around) or Executive ? There can be negative traits/tendencies inside your personality (same for all personalities), if pushed to the excess or if you're unbalanced, not taking care of yourself etc...
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She could also well be an introvert, behing her "Parading Madame" facade, in this case guessing the personality she'd fit in is more difficult.