What makes a text a “commentary”? The question is naif enough to allow for a complicated answer. First of all, let me note the obvious: There is not a single word for “commentary” in Sanskrit, where one needs to distinguish between bhāṣyas, vārttikas, ṭippanīs, etc., often bearing poetical names, evoking Moons, mirrors and the like.
Our institute has had the honour of having here Suganya Anandakichenin as guest researcher. I even managed to convince her to discuss about her research in a short interview. Enjoy her remarks on collaborative projects and on devotional literature!