Display Lock Screen Day and Month in Partially-Supported Languages

Note: As of iOS 16.6.1 (and perhaps earlier), Apple has fixed the problem described in this tip, and lock screens again display partially supported languages.

Apple provides full support, including translations of its iPhone/iPad user interface, in 34 languages, which are listed in the tech specs for each device.  Dozens of other languages have partial support, essentially for reading and writing. 

In iOS 15 and earlier you could have your lock screen display the day and month in most partially supported languages if you put them at the top of your preferred language list in Settings > General > Language & Region.  An example of the lock screen for Welsh (Cymraeg) in iOS 15 is shown below.

While Apple has added many lock screen customization features in iOS 16,  this particular language capability has been lost in the updates released so far, and I have not yet seen a widget that provides it.  It's not possible to take an iOS device back from iOS 16 to iOS 15.

You can ask Apple to bring this featiure back via the feedback channel.