My suggestion is that when adding new applications for Nextcloud, let their developers have their applications translated into native languages by the community in Transifex. I noticed that many applications are in English only, which gives users some inconvenience in terms of understanding. Additionally, Nextcloud itself would gain in quality and appearance.
I think it is also a good idea to add information in Nextcloud Apps in what language the application appears in its detailed description (English, Multilingual). The information should be visible to the user before it is downloaded, not after installation.