Following the work done in T360409: Page status tri-state for pages not marked for translation, it is possible to save the translation state for pages under the namespaces defined in TranslatePageTranslationBannerNamespaces.

This configuration also controls the pages in which recent editors see banners (T360411) about setting the translation state.

However, there is an argument for allowing editors to set the translation state for any page, regardless of namespace, if they access the settings action on Special:PageTranslation.

Consult the community, review, and implement.