Hello,
In order to translate the string “On backorder” with the “Loco Translate” plugin, navigate to Loco Translate -> Hitek -> Choose a language (The language should be the same as your WordPress, for example, if you have the default language in WordPress – English, then you need to create in the Loco Translate the same language, after that the plugin will work properly) -> don’t forget to click the “Sync” button (to synchronize all strings from the theme) before searching for a word and then in the search field write “On backorder”.
https://www.loom.com/share/78637816d2724711b353bf0a82e66c16
Kind Regards