Her name and age (ten years old) were revealed when she was interviewed on What's Your Favorite Word, where she talked about "adventure" being one of her favorite words.
Interview from WYFW
One of my favorite words is "adventure", because it makes me think of a beginning of a big long memory full of laughter and excitement, and a great journey to remember.
In spite of this, she is actually seen later in the Funbots concert instead. Not visible in the initial shot, a later focus on Tim and TJ shows her sitting behind Tim and to his right, on the far left edge of the screen.
Tessa has some short lines in this episode, although she speaks in a different voice than the one used in her FW interview.
- Oak Street lady who has a similar-looking nose and glasses