Sorry Isaac, but to start with I find it really difficult to read such a huge paragraph at any time, but even more so on a screen, so I might be missing a point you are trying to raise.
As I still understand it, the naming convention on WikiTree is that for everyone born in Europe pre-1600 we use the original European Aristocrats naming standard (except for Scotland which have their own standards).
As you note all early medieval sources would be in Latin, and as there were no dictionaries the spelling of any name be it person or place could vary, even within the same document. As such I think we use the (unwritten?) policy of writing names in the modern European language most appropriate to that person, which can be difficult because they moved around (particularly the Vikings) and borders between countries were often very fluid. For instance Sigurdsson, might not have existed as a name in early medieval literature.
In terms of how some of these medieval people fit together, one of the traps is to think that somehow all the Counts of Guines or whatever country/county/manor we are researching, must all be related. Whereas we know that places could be won by force (think Vikings or Norman Conquest) or were a gift of the monarch, and that gift could be easily taken away.
Solely relying on early modern sources (such as Duchesne writing in the 17th century) can also be a problem because although they did start to use medieval material as sources, they were still often supported by members of the nobility, who wanted to retain their genealogical pretensions to more famous ancestors.
The other issue behind your question, which I am sure has been mentioned before, is that we know there are many problems with pre-1500 profiles, but unfortunately there aren't that many people on WikiTree who have been deemed to have the necessary skills and knowledge to fix these issues, and actually fixing the issues takes time. So although it is great that you and other's point out some of the problems, they may not be rectified quickly.