I've noticed a few issues in my world that I think are being caused by the fact that it was created back in 2016. I've looked up some of these and noticed that they couldn't be reproduced and this is the reason why! My issues include:
A Witch Hut that doesn't exist anymore (MCPE-28541)
Some dogs that I can't interact with (MCPE-39371)
Ghasts that are flying around like crazy (MCPE-30588)
Zombie villagers wearing the wrong clothes (MCPE-45586)
Redstone not working around the edges of an Old World type (it worked before; not sure if this is related) (MCPE-34015)
The same music keeps playing in Survival (again, not sure if this is related; it worked before)
Purchased content doesn't transfer between Bedrock devices (MCPE-25371)
We can only track 1 issue per ticket.
Some of the issues you mention are being tracked on other tickets now. See MCPE-50467 and MCPE-42348, for example.
You are welcome to create new tickets for individual ongoing issues. If you do, please mention the older, resolved ticket in your description. However, please do not create new tickets for issues that have been resolved "Works As Intended," like the witch hut generation ticket MCPE-28541.