Display of strings in fallback language

OPEN This issue is open, waiting for action by TomH

If I understood the documentation correctly when language variants are being translated (in this case de_CH) the translation in the fallback language (in this case de) should be displayed, however currently (correcting some of the Germany specific translations of OpenStreetMap-website) I only get the English original source displayed (which in this case is not particularly helpful).

Fallback languages are implemented in MediaWiki, but not in all projects supported by translatewiki.net. You should report this bug to OSM.