In thousands of forums around the world, there is a simple and well known practice.
When a thread / post is moved or deleted, the moderators notify the user / author of what happened and the reasoning behind it.
It is simple, easy, and mostly automated pm / notification /email where the only thing the moderators need to do is choose the reason from a drop down list.
That helps the users understand what the hell is going on. It is so cool...

It would be glorious if you started doing this thing that everyone else is doing since the previous millennium.
That's all. Thanks.