Does anyone happen to know if there is a 8191 node limit on polygons? When I exceed that number, with insert node, my poly is gone. And if I try to create a polygon with more than 8191 nodes CC3+ disappears (read: crashes).
PS: my way around it without having to lose my pieces and parts was to split the element at two points then join (closepath) the loose ends back to a polygon. presumably I could then mpoly them, but i've not bothered with that yet.
I'm not sure of the limit, but I have used the same trick as you to get around dealing with the coastline of my huge continent of my world.
You can have more, as you have discovered by joining two sets with CLOSEPATH, but the basic node editing tools (add node, edit node, delete node) can't operate on these, they don't support entities with more than 8191 nodes. May be other commands with this limitation too.
I never hit this limit at all, even though I export lots of maps from FT3, which is famous for generating thousands of nodes. I don't think the drawing tools trace function is affected by this limit, or there are many maps that I think would have failed for me.
using mpoly or mpoly2 elements can be joined to look like one element, but, with list, you will see they are separate. seems this sort of limit should be in the docs some place. the crash most definitely shouldn't happen though. perhaps i'll mention it to profantasy support.