Firmware link
New firmware has been released for pre-10th generation kindle, I got my Oasis 2017 updated today:
What's New:
New translation languages: Translation support added for Afrikaans, Catalan, Icelandic, Swedish and Welsh.
New keyboard languages: Keyboard support added for Afrikaans, Danish, Icelandic, Norwegian and Swedish.
Performance improvements, bug fixes, and other general enhancements.
I didn't notice any difference regarding the performances and bugs.
I didn't see those languages in the languages setting (but they are available in keyboard setting).