I have pages with several piwik wdigets embedded, which works perfectly fine. The only problem is that every widget that allows to siwtch the view type to goals (clicking the little flag icon) will return an error that view permission is required. Looks like it is not using token_auth.
Switching to type goal shows the "Loading data ..." text which never stops (because of the error that happened).
Keywords: token_auth, view type goal, embedded widget
See #1353 (I added your report there)