How should invented languages be added?

The Na'vi language is a full language, at least according to the trivia on IMDb. But, unlike Esperanto, which was created for real-world use, it's specific to one fictional universe. I think such work-specific languages should be ineligible for the list of languages, at least unless it can be demonstrated that they have a significant life beyond the works they were created for. It’s not helpful to be able to list all the works with speech in, e.g., Molanguese, if all that’s going to get you is "Molang" or otherwise only works in one media franchise. Something as simple as adding an "other" or "invented language" option to the list and instructions to use this in such cases and add the English name for the language as an attribute would be sufficient to solve this problem. However, it shouldn't be used as an excuse not to add real-world languages in which there are numerous films, TV programmes, etc. It could perhaps be used for extinct/reconstructed languages in which there are only a few works on IMDb. For languages still in use but only in very specific places, I feel it would be more appropriate to have a more general category in the list and instruct people to add the specific language as an attribute, rather than throwing them in the same category as invented or extinct languages.