Thanks for the quick reply! The two blog posts are very informative, I didn’t find them on my own before. Perhaps it would be a good idea to link them (the first one should be enough, since it’s a series) from https://docs.syncthing.net/ for example.
What remains unclear to me now is what exactly happens between the scanning and syncing that are described in the above documents. How are the indexes propagated? How exactly is the “best version” determined for each file. These questions have been posed by others as well, see for example what is the "best" version?.
If you could find some time to complete the series with a third post that clarifies these questions then I’d say the blog post series will provide what I was looking for!