Discover is not showing a considerable amount of the translations for application's description. I don't know about the situation of other languages, but almost all Simplified Chinese translations have been missing, despite being fully translated for years. As far as I know, none of the appdata/.desktop translation after 2018 is being used in Discover (I personally re-translated most of them since 2018). For example, GIMP has all proper Chinese translation in its description, but Krita has not. Breeze has Chinese description but it's stuck with an ancient version. Since all application icons and kde.org's application page https://apps.kde.org/ is currently using the lastest appdata/.desktop translation, I assume translation has been properly collected to KDE localization SVN. I suspect it is either Discpver not loading translations, or there is something wrong in KDE's appstream/appdata/.desktop workflow that fails to pass our newer translation to upstream. Breeze in particular, never has the new translation for the appdata name "Breeze" used in ANY KDE applications, including Plasma. This is likely not an isolated issue just for Chinese locale. If you use other languages, I recommend you look for appdata that translated after 2018 -- they might still have not been used. I have tested it under Kubuntu and Archlinux. The situation is similar.
*** This bug has been marked as a duplicate of bug 465897 ***