This translation is contributed by the Centre de Supercomputació de Catalunya (CESCA, http://www.cesca.cat).
The messages_ca_cesca.xml is a translation of the English original messages.xml (revision 1.16).
Actually, it exist one Catalan translation available at http://code.google.com/p/dspace-sandbox/source/browse/#svn/modules/dspace-xmlui-lang/trunk/src/main/webapp/i18n. But its from the Valencian dialect. Our version corresponds with the Central Catalan, the dialect that speak more population. You can consult more information about Catalan dialects in the following link: http://en.wikipedia.org/wiki/Catalan_language#Dialects
We thing that this version (Central Catalan) is not an improvement of the other version (Valencian), it's a new feature. And both versions can exist. The repositories should can choose one of the two versions.
If you need for information about this, you can contact me at firstname.lastname@example.org
Ricard de la Vega