Don't know all the answers but a few observations.
Scenics are very limited and not suitable for events at all.
When I have region crossing problems, it is usually going from a full region to a scenic or a 2x2. Doesn't happen all the time, but a lot of the time. Doesn't happen as much to my partner for some reason. He will be sailing away into the region, but I will be frozen and sometimes even crash.
Sailing around INSIDE a 2x2, not so much problems. Only seems to be on crossing into a different kind of region for some reasonn.
* this is just my experience, others may vary