Yes, the constant split screen crashing is pervasive and almost game breaking for a family that loves playing Minecraft as a group. My observations is it seems to happen to us most often while an autosave is going and someone opens a chest or fights multiple mobs. Split screen almost never used to crash prior to the Nether update.
All villagers in my game have despawned. Never had this issue before the Nether update. Running PS4 2.09 updated this morning for the login screen issue. Like so many other posters, villagers are in a safe, enclosed area with ample light, beds, food, and crafting stations. Despawns have happened in conjunction with raids, when returning from being out of chunk, and when we've been in the chunk but slept. Last villager died as a result of the many game crashes that now plague split screen play.