Thanks for reaching out here in the Community!
Please be advised that Netflix on Roku shows 5-7 relevant languages on most devices based on your location and language settings. For more information about that channel's features and functionality, you'll want to contact the channel provider support directly to inquire further. Many channels on Roku are developed and maintained by the channel provider themselves.
You can reach them here: Netflix Help Center
I hope this helps.
All the best,
Roku Forum Moderator