The biggest problem is that Konami's timelines are sometimes inconsistent. Even based on Konami's information, it seems like Zexen is founded a number of times, along with the knights. The entire events of Rhapsodia and Suikoden 4 are also somewhat difficult to straighten out.
Most of the time, information on this site or Suikox is translated data from some official source-- but the source can be inconsistent. In such cases, there's really not much that can be done. As mere fans, we can't "fix" such inconsistencies.