When starting a new translation in the SX labs instance, "British English" is shown as an option to select next to "English". However, there is no Wikipedia for British English so it was not expected to appear in this context.

The expected result would be to have only languages for which a Wikipedia exist since the purpose is to select the language in which to search Wikipedia articles.

At the time of reporting the issue was not happening on test wiki, so it may be an issue specific of the lans instance (or maybe it has not propagated yet due to the deployment cycles)