During the time when Latin was the de facto language for scholarship in the West, there was no division in philosophy based on national languages. The huge disconnect of most early modern philosophy from what preceded it was greatly intensified by two factors — people started writing in French or English or German instead of Latin, and they started relying on printed books, mainly in their native languages. It took a long time for many older works to become available in printed form. A huge proliferation of Latin philosophical texts just sank into oblivion.
Due to the common European university curriculum in the middle ages, there was a great deal of shared (basically modified Aristotelian) technical vocabulary and training among people who had strong disagreements about everything else (including disagreements with Aristotle). This made it possible for people with very different positions to have extensive substantive dialogue rather than talking past each other. The quality of argument was generally high. So when all this sank into oblivion, it was a great loss.
Some medieval writers were so good at restating arguments they disagreed with that scholars argue about which position they actually supported. (Usually there is a textual indication which opinion is the author’s, but there may be question about whether to believe it, because the argument for a conflicting opinion may be better, and it is thought that some authors presented their more controversial views as not their own.)
The same unfortunately cannot be said for modern philosophical writers. Even great modern philosophers often do great injustice to other philosophers they disagree with, badly misstating their positions. Many people do not even realize that this has not always been true of philosophers. (See also Renaissance.)