I am working on a multi-lingual website where the content editors sometimes make partial translations of a page where the majority of the content is still the primary language (English).The website owner uses Siteliner to check their website and the reports often highlight the partially translated pages as duplicate content.However we have no idea whether Google sees these partially translated pages as duplicate content and applies any penalties to them. We are using the Google hreflang meta in the HTML to identify/ link the translations.I have talked to the website owner who agrees they are only concerned about Google penalising them for duplicate content. I cannot find anything in Google Search Console that suggests duplicate content is an issue.Is there anyway to test a website to see if Google is detecting duplicate content/ penalties are being applied? 
How to test for Duplicate Content penalties from Google
seo;google;google search console;duplicate content