Also known as Schwa with tilde
буква расширенной кириллицы
In the Vinony graph
Vinony's link graph records 279 inbound references to Ә̃, and connects out to Я, Cyrillic script and Ә.
It sits within the topics Cyrillic letters with diacritics and Letters with tilde.
Vinony links it to 9 Wikipedia language editions.