You are probably looking more for technical info, but here is my user experience:
Books are usually added via ISBN or Title & Author, which works OK, but can be bit of a mess sometimes. Different editions regularly get filed as separate books, if people add it as a book rather than as an edition to an existing book and there is no easy way to combine them without opening a ticket. (In Goodreads, if you have the “librarian” role you can edit everything, including combining (or seperating) editions. Storygraph seems to also rely on at least some voluntary librarians to review book submissions.) Fully manual submissions are particularly prone to producing subpar results.
However, some changes can be done by the users directly, which I find great, because my Japanese or German books rarely have all the data or even a cover associated with them. I don’t know where they fetch their data from. I assume amazon.com but who knows.
I highly suspect they are using Google Books as their data source… which is super easy to use but also has pretty poor coverage (at least for Japanese). It surfaces the editions just like they do in StoryGraph.
I’m mostly just curious on how they’ve managed to build up their series information and their additional editions they showcase, beyond Google Books. Book series information, amazingly, is not to be had in either Google Books / Amazon API, which is a huge pain.
That’s helpful context on the issues you’ve encountered though and pretty inline with what i’d expect. Fully manual input i’m pretty wary of as well.
Edit: It’ll be an interesting challenge to try and figure out a good system that’s more automated than the current one and allows users to help a bit more with content management, without falling off the rails. I’m pretty sure we’ll have to address the ‘edition’ issues as well, so this may turn out to be a larger initiative than I thought. We’ll see.
I’ve added my Japanese books via ISBN and it’s mostly worked for me. However, some titles I’ve added are still missing information so I usually add that manually. Unfortunately, once that information has been added once, if I notice a typo or need to add other information, it won’t let me do it. One would have to use the “Report missing/incorrect information…” option. I also don’t have the option to edit the title for books that are multiple volumes of a series.