Thanks for the quick repsonses, both of you! And Echo, why do something the easy way when you can do it the hard way?

IT WORKS!!! I was indeed missing an interaction, but not the one you think.

With the exception of the biotech station (i.e. a multi-tile object that does funky stuff like generating vials *shivers*), none of the career rewards I looked at had an equivalent of be teacher/pupil, but just the regular teach/be taught ones, and this confused me thoroughly at first. BUT, then I remembered what Echo had said about the pie menus and that parameter in the "Teach - Init", so I had a look at those objects again - and paid a bit more attention this time. It turns out all of them has two versions of their main interaction ("contemplate statue" in my case), one "normal" and one hidden, and the hidden one also had "nest" checked in the TTAB. And that second "Teach - Init" parameter? Was referring to the hidden interaction in all of the objects I checked.

So, I added another "contemplate statue" interaction, hid it from the pie menu and checked "nest", and made that "Teach - Init" parameter refer to this interaction... and now it works! Pupil is being properly taught, and teacher is teaching, and fun is being had by all!

Thank you SO much for your help!!