The relevant message is wikibase-reference-formatter-snak-retrieved, which apparently hasn’t been translated into Catalan yet. (It doesn’t have “data-bridge” in the name because technically it can be used beyond Data Bridge, but that’s probably why it was missed during the effort to translate all Bridge-related messages prior to deployment.)

Edit: It’s also in the Wikibase Lib group rather than Wikibase Client. Special:Translate link, filter for “retrieved” (not sure if there’s a way to link to it directly).

Message translated, I missed it. But if I change my preferences to French or German it still shows "retrieved". It seems it comes from elsewhere.

No, that’s because the reference is always shown in the wiki content language, not in the user interface language. If you take the URL of the API call from the browser’s developer tools, and manually change the uselang parameter (example), you get:

Integrated Taxonomic Information System. 31. August 2004. Abgerufen 22. Oktober 2013.

Thanks for translating the message! It should show up on-wiki next week.