I have also successfully used c:import with jsf. My problem occurs with facelet pages. I have faclets pages that need to import content from outside of my container. When I look at the doc, facelets only supports 4 c: tags and import is not one of them.
https://facelets.dev.java.net/nonav/docs/dev/docbook.html jsp:include and directive include won�t work in a facelets page. In addtion, they will not pull pages from outside of my container.
I think I�ve finally arrived at a solution. I'm going to have to write a custom tag that mimics what c:import does. I still think I may be missing something. It is very surprising to me that faclets does not support c:import.