We're still figuring out the whole workflow of translating the website, so bear with us. The idea is that we'd post all the source texts on Weblate, and leave it up to the translators as to which posts and pages are worth translating.
You can see the translated site on the staging site, that updates whenever new code/text/translations are merged in:
We have to nail down the whole automatic deployment to https://f-droid.org, so that's a bit slow to update right now. @pserwylo has done most of the web programming for the localization. @grote @NicoAlt and I are doing bits and pieces.
As for the duplicated app translations, I wasn't able to find the translation sources for those apps, so I scraped them from the web. It is a somewhat random collection of the more popular apps in f-droid.org. It is fully possible to use the upstream translation if they add them in a standard form in the source repo:
We want to manage as few app translations as possible, but some are very unlikely to ever include those files in their source repos, for example, Barcode Scanner. For apps that do have their own translation files, we should move whatever we have to their source repos.