Yes, absolutely. Our app uses the Facebook Marketing API to query interest suggestions. That is fully approved usage of the API's functionality - Facebook wants developers to use their technology to build value-adding services like we did. 


This is not a loop-hole or a hack that will eventually be shut down by Facebook, that's why they neatly document how it should be used in their developer documentation.


Next to that we've received Facebook's explicit approval of the Ads Insights API to be able to show interest level stats, that are hidden in Facebook Ads Manager.