I am trying to change the navigation sidebar in a Media Wiki 1.5 environment installed with Romanian as default language. I tried editing the MediaWiki:Sidebar page, which did come up, but the change does not show up in the interface. Do I need to address a Romanian-specific namespace (and if yes, what is that?) or do I have to mess up with the php files?

(this is just my best guess, apologies if you have already tried this) In "MediaWiki:Sidebar", do you have something like "randompage-url|randompage" somewhere in there? If so, and you change "MediaWiki:randompage" from "Pagină aleatoare" to "This is a test", does it show up in the interface? You can also change "MediaWiki:randompage-url" to point somewhere else. (I.e. MediaWiki:Sidebar is just a form of indirection, it's not the literal text that shows up in the interface).

All the best, Nick.