Respectfully, this is not a resolution. "Won't Fix" is not acceptable to me and I would bet many other players. You closed 30 plus tickets that are all saying your game has a problem. Deal with it. This attitude is why I am abandoning Bedrock. Thanks for the fishes... almost.
PS My realm does not need to crash for your code to forget where entities are and despawn.
I can confirm that my villages are despawning in both my iron farm that is at y 225 and my villager breeder. I have logged in the server and found 5 of 14 missing from the iron farm and probably 7-9 missing from my villager breeder. Oddly enough it does not happen to my iron farms that are at y 100 or below. Have not tested y values explicitly, but figure I would mention that. This is on version 1.2.7 currently in Windows 10 version.
I also am confused at this move by Mojang. Why are you trying to brush this one under the rug and not fix one of the more important game mechanics? Villagers and entities should stay in the world if you interact with them correct? Why should chunk borders be an exception to the rule. Game crashing is not involved in anything that I was reported here. Regardless this is your game to fix. "Won't fix" is unacceptable.