Dear Everyone,
Following my attempts to create and learn Context's ways to manage fonts, I
would like to ask about the following:

I've created the structure for fonts in texmf-local folder and after
running scripts they are listed. The output for Roboto Flex is as follows:
identifier                          familyname   fontname
 filename         subfont   instances

robotoflex                          robotoflex   robotoflexregular
robotoflex.ttf             thin extralight light regular medium semibold
bold extrabold black extrablack thinitalic extralightitalic lightitalic
italic mediumitalic semibolditalic bolditalic extrabolditalic blackitalic
extrablackitalic

What is the proper way to use family name or font name to create a
typescript file and a goodies file to take advantage of optical sizes.
Google's Roboto Flex is an upgraded Roboto as a variable font.

I know that this topic has been discussed many times and I've read the
fonts manual but still have these questions. Most of the examples are
rather ready solutions or templates but not always cover ways how to figure
out values from scratch and how they correspond.

Thanks for help,
Pawel