Thanks!
Great to hear you're using it for lectures. I always thought it could potentially be strong for that, though I have never tried it (which is funny, seeing as how I am a lecturer too).
The language that is there now is little more than an experiment. It was motivated by wanting to make the idea of a spreadsheet language more visual, I never liked the way Excel does it. Mixing code with data has its own issues though, and I am not sure if it is appropriate for everyone.
I am still not sure which of the many possible ways is the best way forward for programmability of a treesheet. I have some options on the google moderator page.
Wouter