I have been able to reliably recreate villagers glitching through walls to enter beds if the are falling (or at least airborne) and the bed is adjacent to the wall on the opposite side. I discovered the bug because a villager glitched in to a room through a wall to enter a bed because it had jumped while going though an open door on the other side of the wall. 

Attached is a video of both occurrences I was able to capture in a test area.