Yes, "Calibration Software" is for generating calibration products. There was a general desire to keep names short, but adding "Products" to the name would be reasonable (while something like "Products Generation" might be less desirable).
The distinction between Science Pipelines Libraries and Plugins is that the former are part of every release and distribution; it was thought that various combinations of the latter may be released or distributed, and they might be released independently of the Libraries. Plugins, in my mind, include things like meas_ and obs_ packages that fulfill more-or-less-defined interfaces to general frameworks. In theory, all Tasks could be considered plugins, but most seem so fundamental that there's no reason to split them out.