Here the filter is copying the text the name of the filter and does not find
https://baza.cn.ua/admin/shop/products/filters/?filtername=%D0%9C%D0%B5%D0%B6%D0... %D0%BD%D0%B0%D1%80%D0%BE%D0%B4%D0%BD%D1%8B%D0%B9+%D1%80%D0%B0%D0%B7%D0%BC%D0 %B5%D1%80&ok=%D0%A4%D1%96%D0%BB%D1%8C%D1%82%D1%80%D1%83%D0%B2%D0%B0%D1%82%D0% B8
although partially found
That is, you made a mistake
It turns out all the same that this is a multi problem
1. Can you remove the filter for another language or somehow add a footnote that the search only works in Russian?
2. I have RBM base language why doesn't it search for RBM ?