This is still an issue in 1.6.1 of bedrock. Creepers will not spawn in 1.8 height areas
I am on Bedrock v1.2.13 and can say that this seems to still be an issue as of May2018. I have trading hall and iron farm with a bunch of villagers lined up in 1x1 cells. They all have glass over them and the walkway in front has half slabs of cobble above. BUT I came in to find that 4 sequentially in line villagers in their 1x1 cells had been turned into witches. The only way I can think this happened is that lightning came through the ceiling of slabs or glass+slabs and struck them.
I can confirm that this happens with any tool/weapon with mending. I am on realms with bedrock and play on that realm on android (v1.2.13) and xbox and experience it on both. I typically notice it when I am at my blaze spawner or skeleton spawner killing lots of mobs to gain lots of xp quickly for the purpose of repairing the tool with mending. It can happen both when xp is picked up one at a time or a pile of them. When it does happen, it appears that the xp that was picked up during the "glitching" is not applied to the tool's durability. It will stop on its own after a few seconds or can be stopped right away by changing tools but the xp that was trying to be applied still seems to be lost.
this has been a persistent issue for bedrock for a few versions now... at this point there is insane lag spike when playing on 1.10 and on Realms for me. Sometimes have to wait like 30secs to open. I hope this is a top priority issue for Mojang. (Yay "Bug"rock!)