Just noticed a bug with Roboto light. If I sync just that version of the font and then start using any Google application on Chrome is messes with the font used on said application. For example: Google Analytics, Google Hangouts, etc. My company's website also uses Roboto as the main heading font and it replaced Google's Roboto with Typekit's version, causing some glyphs not to show up properly.
I'm sorry that you ran into trouble with this. It sounds like you are seeing an issue where Google applies the version of the font you have synced from Typekit instead of using one from their web font service:
The conflict happens because of how the Google Fonts CSS works. Google looks for a locally-installed version of the font first, as you found, and will use anything match it finds in place of the web font file. If the local font has a different character set or smaller language support, the website doesn't display as expected.
Unfortunately isn't something that we can solve from the Typekit side. Google Fonts would need to change how their CSS uses locally-installed fonts to avoid the conflict with any locally-installed version of the font.
The workaround is to remove the version of the font you have synced from Typekit, so that Google will apply the web font to the site again.
If that doesn't sound like the issue you're seeing, please send me some more details on the problem and we'll look into it further. Thank you,