Is there a way to open a variable font and keep the masters and axes information to check how it works?
That is currently not possible. I’ll add support for variable fonts but Variable fonts can do quite different things that can’t be put into the Glyphs data model so it will not be good for debugging. Have a look at the ttx file.
Here’s a link you that allows you to download a variable font with masters and axes info:
I found it helpful, good luck, t