davelab6
https://developers.google.com/fonts/faq#how_do_i_contact_goo...
https://developers.google.com/fonts/faq#what_does_using_the_... was updated today, confirming Google Fonts doesn't log IP addresses.
Given that, it's unclear to me personally what the difference is between Bunny Fonts and Google Fonts.
It's both completely ubiquitous and invisible.
That can be done with OpenType Variable Fonts (eg Decovar and Amstelvar) but is not commonly done with them (eg OTvar fonts with just Weight and Width axes)
Its more common that parametric fonts are made with 'generative font' formats, like metafont and www.Prototypo.io, where there is a turing complete programming language that controls and generates the letter shapes.
And even then, the typefaces made with metafont are often very poor designs compared to those draw in a GUI in a 'dumbfont' format.
Adobe Multiple Master, then TrueType GX, and now OpenType Variations, are a 'best of both worlds' compromise; the drawing quality of visually crafted outlines, and the continuous-space-type-family-in-1-file typographic flexibility of metafont.
Metapolator (a project I co-founded) uses Hobby splines and has not been used so far to develop Variable Fonts AFAIK.
I filed an issue for your nice suggestion, https://github.com/TypeNetwork/fb-Decovar/issues/6
Decovar – A multistyle decorative variable font
Decovar, a new “variable” font that shows off the latest OpenType font format
But there is a js version on http://fontly.com/sandbox/spiro.html
But expanding single styles into families is not as easy as it should be. That's why I help start http://metapolator.com which takes www.metaflop.com and removes the 'write metafont code' part of the process.
As you say, if you want the fonts to be better sooner than Google, you can pay for it - either by commissioning the designer to improve the open source fonts or by going across the street to a paid web font service.
Typism is dead, no one worked on it for ages.
http://prototypo.io is new, active, libre, Angular, on github, but! it suffers from the classic problem of processing and such; designing visual things isnt best done by writing code. Its why metafont didnt catch on - https://www.google.co.in/search?q=why+metafont+didnt+catch+o...
That's why I help start http://metapolator.com which will become a much more powerful online font editor, because it allows you to design typeface families instead of letters.