I think some google fonts don’t render because the system doesn’t have them in stock. Some one asked me the same and this is what I wrote
Depends on the phone you have and the browser you are using. What happens is that when the system doesn’t have the font you want, it uses a secondary font. Happens the same with me, when I use tahoma, it changes to arial in mobile phones, also some windows computers don’t have tahoma so they use a secondary like arial.
Thats why when you are selecting a font in the settings they usually have more 3 fonts, for example : helvetica neue, helvetica, arial. This is so that if the system is missing helvetica neue, it uses instead the secondary ‘helvetica’ if helvetica is also missing then it uses the tertiary ‘arial’ and so on.