It's been a while so memory is hazy.
This does sound like dominant Te.
Ah, you said you didn't see Si. IMO, this is Si<->Ne dichotomy: stability over the unknown [possibilities].
Nope. Sera fears deprivation [nothingness] because she's a glutton: freedom, autonomy, the ability to experience new and wonderful things ~ viva la revolucion! She doesn't play nice with people because that would require compromise and abiding by spoken and unspoken rules of the game - antithesis to freedom. There's also an aversion to sadness and reflection (giving the past some thought), hence her fear of the fade - the realm & spirits representing the past, reflection, introspection. Cassandra fears helplessness because of her sense of duty [superego], strong expectations set for herself.
They are both similar in that both have a strong sense of autonomy and both are tied to one another in terms of health and growth. Sera can use the discipline and focus and grand sense of duty [vision] for what she wants, rather than participating in petty revenge schemes, akin to spray painting graffiti on a building and calling it revolution (weak Te). Cassandra can use a bit of spontaneity and indulgence so as to lower her blood pressure and live to a decent age. I think Cassandra's tarot card (romance variant) symbolizes her path to growth - spilling of the chalice representing caution to the wind, passion & excess.
She could be. I thought she was too willing to play the game to be TJ. Her attention to affiliations and unspoken social dynamics, while representative of her work, is too tedious for TJs.