There is also a chance that it's not reproducible when running the app from Xcode. My two friends confirmed that this issue occurs in my app but there is a small chance that it happens only when you publish the app.
You can check my app: https://apps.apple.com/us/app/smog-poland/id1367444922. WatchOS app is paid (in-app), but you can add widgets without activating the app. If you go to widget configuration you should see the fallback labels in Polish.
Topic:
App & System Services
SubTopic:
Widgets & Live Activities
Tags: