When editing badges in the sitelinks section on an item page using a language which does not have labels for the badge items, only their plane Q-ids are shown instead of a label in a fallback language. This makes it impossible to set a proper badge using such a language.
Try for example: https://www.wikidata.org/wiki/Q2?uselang=de-ch
Before the first click on edit, there are fallback labels, but after clicking edit once, only the Q-ids appear.