Trade node connections are quite easy to mod in.
MEIOUandTaxes1/common/tradenodes/00_tradenodes.txt
Ctrl+f: "north_sea_node="
Scroll down a little and place cursor at the end of line 1653 (use the program notepad++ it's a godsend for doing stuff like this), press enter, and paste the following:
outgoing={ name="atlantic_node" path={ 2054 1857 } control={ 2737.000000 1953.000000 2634.000000 1832.000000 2575.000000 1825.000000 } }
The finished product should look like this, where the highlighted section in the picture is what you should paste into the file. The connection path even looks kinda pretty if I do say so myself.
To answer your original question, trade nodes were changed for balance purposes. I believe the North Sea -> Channel node connection specifically was broken because the Channel node was laughably overpowered in previous versions of the mod. In my experience, England [especially a player England] was able to easily dominate both the North Sea and Channel node which gave them a very large income from trade; Denmark and Friesland couldn't compete in the North Sea due to the amount of trade power England had in Scotland, North England, and Ireland, and England could send huge amounts of trade power upstream from the Channel node. It was pretty damn overpowered and I'm not surprised the connection was broken. Since EU4's trade mechanics are so blatantly nonsensical to begin with, the MEIOU modders likely don't particularly see an issue with having nodes either not have or have connections where one might think such connections should or should not exist, respectively.
the easiest fix is just to edit your save to get rid of the disaster. First get notepad++ then open your save with notepad++. hit ctrl+f search for "human=yes". once you're at human=yes then search for "disaster_" there should be a disaster_progress and disaster_started. the first should have a lot of 0.000's, find the entry that's 100.000 and change it to 0.000, the next should have lots of 0's find the entry that has a 1 and change it to 0. save your save file and you won't have the disaster anymore
https://www.amazon.com/After-Tamerlane-Global-Empires-1400-2000-ebook/dp/B003Z9L4O4 suggests Timur / Tamerlane died in 1405.
The Byzantines never referred to themselves as Hellenes, as others have already said. They always called themselves Rhomaioi, or "Roman". They called the language they spoke "Roman" as well, even though we would call it "Greek" today. They called their pagan Classical ancestors Hellenes, and referred to the language they spoke as Hellenic. Knowing how to write in the Hellenic style was considered a sign of high education and culture during the Byzantine period.
If you're interested in this subject, I recommend <em>Romanland</em> by Anthony Kaldellis. He's an academic Byzantine historian, but I find his books to be very approachable.