Thread:Support/Language names not in Unicode CLDR

Hello! We're working on a template for language names at Catalan Wiktionary. We use  which is mw:Extension:CLDR (Version 4.0.0 (CLDR 22.1)). I've read FAQ, but I can't find at Unicode the "Extremaduran" language (Portal:Ext), so I don't know if it would be correct to apply there the Catalan and Spanish translations (Extremaduran is English). Look at this: How can I make  to give "extremeny" (ref1, ref2), and   to give "extremeño" (ref1)? Thanks!