You touch on an important point here. Even if you were able to gain full access to the data behind say Confluence, the schema is probably very specialized to th

You touch on an important point here. Even if you were able to gain full access to the data behind say Confluence, the schema is probably very specialized to their client, contains lots of tech debt, and design is probably very opinionated. You would most likely find it easier to just write your own schema rather than integrate with theirs.