with the villager at Y=319 and standing at Y = 320 and trading with the villager does not get the achievements. you cannot get the villager to stand at Y = 320 they will not clam up the last block. you cannot put a minecart rail at Y = 320 and have them go up to it. I have seen that the java edition will give you the achievement with the villager at Y = 319.
Oh and next time someone reports something, don't replay to it then resolve the issue at the same time. Here is the original issue
Please do not duplicate your own report (MCPE-177275). If you have new information, you can edit your original report.