I am getting this warning in Eclipse:
NLS missing message: CANNOT_FIND_FACELET_TAGLIB in: org.eclipse.jst.jsf.core.validation.internal.facelet
This was also the case when I imported a JSP taglib, for example:
I closed the project and reopened, and it worked!
Eclipse Java EE IDE for Web Developers. Version: Indigo Service Release 1 Build id: 20110916-0149