If any of the remaining Castles.com cites are also supported by another cite, then remove the Castles.com one. Add a "Further reading" section and put the Castles.com link there. Well, that's what I would do, anyway. I know that the webpage is supposed to be a transcription but, well, how do we know that it is an accurate and full transcription?
There were a lot of people with experience who chipped in with comments as this article developed, all of whom were pleased with the outcome (as far as I can recall). It does not need any big reworking. Oversourcing can be an issue but I think that in this instance it was pretty much all needed unless the decision was taken to rely primarily on Castles.com. Of course, no article is ever finished ... -