The issue is still discussed with our developers, What you are experiencing is an intended behaviour with WPML and YOAST. However there are some SEO audit issue our developers will make a decision on this after detailed investigation and checking with SEO best practices.
As of now the stand is that with duplicate option the canonical should always point to the default langauge url to prevent SEO penalities.
Since there is difference of opinion in handling duplicate contents and we are trying to get this working with more reliable resources from google. Also just in case if we could not arrive at any solution we will try to add some filters the code to make it work for differnt clinet.
As of now the status of the ticket is still being discussed by developers, I could not say how long this would take as it involves adding a new feature to the plugin which never exisited before.
I mark the ticket as escalated to developers and update once I have more news to share.