Summary
On Bedrock Edition, cave vines can be considered berries, and sweet berries can be pollinated by bees. But the cave vines cannot be pollinated by bees. This is also a parity issue with Java Edition since MC-214127 would be fixed in the next snapshot.
Not sure if this is fixed or not in the latest beta. Still cannot get bees to pollinate cave vines. Was able to get bees to pollinate other flowers though