One thing that probably should be considered are non-surface villages. Villages don't depend on sky access anymore and thus can be created underground in the overworld, and raids should be able to work with them as well. In the nether there are only cave spawns, and the raids on villages there would no longer work if they were entirely surface spawns.
Spawning rules for underground raids should probably be modified, or another means of finding them outside of the horns you hear when they are near might be helpful. But removing the cave spawns entirely would break them.
(going to move that comment over to the bug report devoted to underground raid spawns)
One thing that probably should be considered are non-surface villages. Villages don't depend on sky access anymore and thus can be created underground in the overworld, and raids should be able to work with them as well. In the nether there are only cave spawns, and the raids on villages there would no longer work if they were entirely surface spawns.
@Harrison Moore, indeed. The current bugged behavior is that Villager Homes are not being recognized in any dimension other than the overworld.
Still affects Win10 1.5.0
Confirmed for v1.5.0
See also: MCPE-35114
Unobstructed view of the sky (following the same rules as beacons) is supposed to be the requirement for detecting a house for a village in any dimension. But villagers never end up reproducing or staying inside what they should be detecting as a house at night. It seems that villager mechanics are disabled for dimensions other than the overworld.
I had this experience in Win10 Bedrock, as well. I tried making an underwater base where I found a ruin's chest and was surprised to find that all of the sand around me kept flooding my newly formed air-space! I couldn't tell if it was a feature or not. Guess I know now.
Porting over the glowing effect from Java , whereby all of the raiders get a glowing effect that can be seen through blocks when the bell is rung, would be simple solution here to have it both ways. Ie: to on the one hand, allow for the mechanism to function underground and in the nether as is currently intended (sky access is not part of a village.) While on the other hand, to always allow for the player to find all of the raiders.