Cunning Linguist: Downplayed, has shown to have a talent for languages, and speaks English and Spanish fluently as well as a little of most Romance Languages. Being one of a few polyglots means it is far less noteworthy than the trope would imply.
Power Incontinence: As of after Romania, her wandless patronus tied her magic closer to raw emotions. That coupled with the stress and crap she went through is making her magic harder to control and more likely to have strong violent outbursts. Lita is scared she'll end up like Ariana Dumbledore because of this.
The Nondescript: A played-down version, Lita is not really described as being nondescript per-se... but she has brown hair, and is the only currently active character with boring brown eyes. She's of relatively mixed heritage because of being Spanish, meaning her melanin levels can vary a lot, also providing her with the ability to look vaguely Caucasian instead of very notably one race, and could probably pull off passing for a number of fake nationalities. Lita is shorter than most other characters— but that's because most other characters are described as being relatively tall, and she usually slouches. She's actually average sized for a Spanish girl. Lita is not ugly, yet she's not particularly pretty, and she's of average build. Her behaviour and personality, as well as her youth, are the most notable things about her, and those can easily be disguised.
This would be very good if she'd WANTED to be a spy. She looks like some 85% of the female population in most Spanish-speaking countries.
Hidden Depths: So far her team mates know her as an angry drunk with a large shotgun. She has a doctorate in Comparative Literature, a Masters in Polish Literature, and several medals for bravery as a police officer. Presumably Karla is aware of this.
Hulk Speak: In English, the worst of her languages
Ascended Extra: word of GM is that "Karla" was intended to be a nom de guerre adopted by an existing character as a nod to The Quest for Karla, until it was recognized that it wouldn't work and she took on the role for herself.
The Chessmaster: a near-job requirement for her job, namely, the head of one of the Ministry of Magic's intelligence apparatuses.
The Faceless/Master of Disguise: a variation. It is stated that she usually goes around under the disguise of Polyjuice, and her true appearance has not been seen.