From version 2.5.0 of the Kocuj Sitemap plugin all deprecated filters will be removed. All of them has been flagged as deprecated from 2.0.0 version, so there was enough time to migrate into new filters.
Additionally, from version 2.5.0 all other methods for creating custom support for multi-lingual plugin (without any interface and with \KocujSitemapPlugin\Interfaces\MultipleLanguages interface) than the current one (with \KocujSitemapPlugin\Interfaces\Language interface) will be removed.