> I've always wondered about the accuracy of the book

It's a work of fiction. I suspect it is as accurate as a japanese book about america or hollywood's depiction of the wild west.

Early on, the book describes blackthorne as being a head and shoulders taller than the locals. That may be true in 1900s england, but in 1600s ( really 1500s ) england, an englishman was generally closer to 5 feet than 6 feet. And as you noted the comical suicides and extreme behavior of the characters doesn't seem realistic at all.

Shogun probably reflects 1600s japan as well as Fargo reflects 1990s Dakotas/Minnesota ( and that was based on a true story! ).