Thai or Arabic UI for Adobe Reader DC?

Hello,

I am adding language support for an Adobe add-in.  I have added support so our custom menus in the plugin are localized for Spanish, French, Japanese, and Chinese.

I now need to add Arabic, Thai, Italian, Russian, and Portuguese - Brazilian.

I am using the following Adobe reference to obtain the correct "Locale" code:

https://www.adobe.com/devnet-docs/acrobatetk/tools/AdminGuide/language.html#x-and-dc-language-support

I do not see Thai in the list and the only Arabic entry is "en_AE" for "Middle Eastern English for Arabic."  Can I get Adobe Reader UI to switch its menus to Thai or Arabic?

Also, for some reason, I can no longer switch "Application Language" in the Adobe Reader DC "Preferences - Language."

Previously I could select "Choose at application startup" for "Application Language." Then the next time I loaded Adobe Reader, a dialog would pop up where I could select "English" or another language.  I had tested this in the other language support I has previously implemented, but now I cannot test because when I reopen Adobe Reader the dialog to switch languages does not pop up.

Regards,

Ralph Ocampo