It turns out that it was just a glitch and I tried loading up my world again, everything,s fine. The trims now show up. I apologise wasting your precious time.
If there is no gap and the zombie and villager are standing on the same y-level plane then yes, zombie can attack, but even at ylevel which is just 1 less, the zombie doesn't sense villager and stops being agressive towards it
You cannot downgrade to previous versions if you have bought Minecraft.
RESPECTED MCQA,
Yes, this issue is still being a problem in the latest versions as well.