This is a Typekit font issue not Muse or widget issue. According to Adobe support:
The original bug that triggered this error for many customers from mid-July through mid-September 2015 was fixed by an update to CCLibraries that was part of an update of the Creative Cloud Desktop application that went live in mid-September 2015. Since that time there are still a few customers encountering this error. In those cases the cause appears to be a mismatch in the login status between Muse, Typekit and the Creative Cloud Desktop app.
- To correct this mismatch please do the following:
- Quit Muse
- Go to the Creative Cloud Desktop app and Sign Out from Preferences (it's in a menu off the gear icon).
- Quit Creative Cloud Desktop.
- Relaunch Creative Cloud Desktop.
- Sign In.
- Relaunch Muse.
At this point you should be able to publish, upload, etc. and your Typekit fonts should work without errors.