In T265297, only the code osa-latn was added. The code osa, for Osage in the Osage script should have been added, too, as I had already said on that task.

It's definitely needed for monolingual values. I can immediately think of two items where text in this code would be useful: Q264400 (a person depicted on U.S. coins with name in the Osage script) and Q66316924 (a major motion picture with a lot of Osage dialogue and an official Osage title that appears in the Osage script in the promotional material and in the film itself). Very likely, there are many more items where values with text with this code will be relevant.

It can probably be used for lexemes, too, although I don't intend to work on it myself.

Since I'm a language committee member myself, I don't mind waiting for approval from another committee member.