Book metadata is one of the more challenging areas for Founce. The metadata is generally set up to support finding books, which makes a lot of sense given that bookstores are the primary intended consumers of that data. The publishers tell the bookstores about a new book that's available and the bookstores add it to their database. When a customer asks about it, they can look it up in their database to see if it's in stock or order it. This is a simplification of the process, but hopefully it's helpful.
Founce is attempting to do something beyond the basic case of finding a book that you already know about, which requires a higher level of organization and greater understanding of how the data is interconnected.
First, Founce wants to associate all of the books by an author with that author. Creating a list of books by a given author seems like it should be simple, but it's non-trivial. Book publishers generally provide author names and maybe a bio, but nothing that could be used as a unique identifier. This would be fine if there was a restriction that prevented multiple authors from publishing under the same name. Frequently, authors will use a middle initial or pseudonym to prevent the ambiguity. Unfortunately, the ambiguity exists and Founce does what it can to figure out which books go with which author.
Secondly, Founce wants to create a list of creative works (i.e. books, music, TV series and movies) for the people that made them. It's nice to see a list of books for an author, but even better to see that they wrote some movie screenplays as well. Also, maybe an actor or musician wrote a novel or memoir. Founce aims to show all of the books, albums, TV series and movies for an individual in a single list. This greatly expands the amount of ambiguity since there are more likely to be actors or musicians with the same name as an author.
Most of the time, either there is no ambiguity or Founce is able to figure it out through a variety of methods. These are the cases where the books for an author show in the list for that person along with any albums, movies, etc. If Founce can't figure out exactly who the author is for a book, the fallback position is to keep them separate and show multiple entries when needed. This is most apparent when an article mentions a number of books for the same author. In that case, Founce will show all the book titles including those without an association to an author. That means there may occasionally be several entries for the same author showing up on the same page, each with a different book mention.
Although this isn't perfect, it generally works pretty well and automatically improves as the data gets updated. There are improvements to Founce that can be made as well, but as long as there is ambiguity about exactly who an author is for a book, there will still be issues.