What is a new namespace? What is old?
There are no different between those. The tld files (as well as corresponded facelets files) are 100% generated. There is no any difference inside those files except the different URIs.
You can experience some glitches if old and new libraries are in the same class when the application is running. However, it is abnormal situation.
Ok, call me a liar. I went back to old namespace references and cannot duplicate initial problem.
I may have a caching issue with a4j:form vs. h:form changes. Caching issues make me crazy.
Sorry for the post.