I found the statements below in my logic textbook. To me, they sound absurd. Surely, there was information and important schools of thought outside of Enlightenment Europe. What historical evidence (if any) is there to support a counterclaim, that in fact, Leibniz was not a true know it all.
I included a second claim from the book that suggests Leibniz understood the "relation between soul and body". Are claims like this still common in academic circles? Is it fair to say, these claims are Eurocentric? Was Leibniz's philosophy even widely accepted in his own time?
"Gottfried Wilhelm Leibniz was a polymath who knew virtually everything that could be known at the time about nearly every area of intellectual endeavor." followed by "in metaphysics he created the famous theory of monads which, among other things, explained the relation between the soul and the body.
Hurley, Patrick J.. A Concise Introduction to Logic (Page 324). Wadsworth Publishing. Kindle Edition.
You should post this question at r/philosophy, for a longer answer. Leibniz wrote a lot ( so much that a great deal is apparently not cataloged), and someone there might specialize in him who could say more.
As to whether he defined the relation between soul and body: that was one of his goals. Leibniz was a system builder. He wanted to describe how the world worked, at a very basic level, and so created a hypothetical system and then argued why it would work. This hypothetical system was supposed to deal with a very difficult problem: God exists. but how does God actually operate, to effect changes and control things? Spinoza had effectively argued that God could not be a personal God, a man in a white robe intervening with miracles, because miracles made no sense ( for example, if one miracle happens to save a holy bishop, wouldn't God continue sending miracles to continue to save the bishop?) By having God operate at an atomic level, through monads, Leibniz was trying to reserve a place for a personal God, someone who could seem human. The alternative, an impersonal God , was very disagreeable. And still is, to many conservative Christians.
As to knowing virtually everything in his age, Leibniz was definitely one of the brightest minds of his time, and knew it. He was a professional mind: always looking for useful ideas that someone important would buy, that would convince king or duke that Leibniz should have a job around their palace, or in their library..... An argument for a personal God was just such an idea, desired by many people, in order to fit with the Christian theology of the time, but he also proposed many solutions to many other problems: for example, Louis XIV wanted to wage war in Europe, which was damaging. Leibniz thought it would be possible to send Louis off on a crusade into the middle east, against the Turks. And of course, Leibniz was a co-discoverer of calculus, along with Newton.
here is a nice summary of Spinoza vs Leibniz's theology. A very well-done book on Leibniz's career and how he was influenced by Spinoza is Matthew Stewart's The Courtier and the Heretic: Leibniz, Spinoza and the Fate of God in the Modern World.