Explanation of how to use parama-roundup to use Flex alongside a static font

I believe one of the use cases for parametric axes is to be able flex a parametric font like Roboto Flex to better harmonize with a non parametric variable font, or even better, a static font; and to do this, the typographer needs to know the parametric values of the instances/styles they are dealing with, using a tool like https://github.com/FontBureau/Parama-roundup

I would like to be able to link to a full explanation of this theory and demos of it in practice.

I wrote,

> Any individual font style, either a static font or an instance of a variable font, can be calibrated with parametric axes values, as the axes ranges are “absolute” values that can be compared across styles. For developers, the [parama-roundup](https://github.com/FontBureau/Parama-roundup) Github project by Font Bureau demonstrates how to do this calibration.

This says the 'what' and the 'how' but not the 'why' or a demonstration :)