A link to some past issues of the Journal of Celtic Language Learning was posted at http://forum.language-learners.org
http://www.naaclt.org/past-issues.php
New to me (and the person who posted the link). Obviously only some are directly to do with Welsh.
I noticed one article by the always-interesting David Crystal:
http://naaclt.org/resources/JCLL_2006_vol11_p5-19.pdf
“Revitalizing the Celtic Language”.