Sirionó isn't supported yet as a language in Wikidata, thus it is not yet possible to add labels in this language.
I saw that there is a similar task for Northern Thai (T93880) and it seems that task is blocked because the name of the language in Northern Thai is not given.
The Sirionó word for the Sirionó language is "mbia cheë".
Basically I would like to add "mbia cheë" in the Wikidata item for the Sirionó language.
- language item: https://www.wikidata.org/wiki/Q3027953 : native label writing system speakers