Make detection of not supported languages more robust (#20111)
None. Fixup of PR #20100
Summary of the issue:
Synthesizers may return None for normalized languages, and this is not addressed in #20100.
Description of user facing changes:
None known.
Description of developer facing changes:
None.
Description of development approach:
Considered the situation where the normalized language is None, improved the function to check if a language is supported, and added unit tests for this function.
