One thing to bear in mind with family sharing is make sure you trust the person who you're family sharing with as a ban on their account can affect your account also.
I would suggest contacting our Support team over this. If you've levelled up The Trapper to P8, you should definitely have all the perks available at T3 on all of your other killers (even if your Trapper was at P3).
For right now, the merge feature is disabled - it's being worked on and will be back as soon as is possible...the cross progression is between, Stadia, Epic Games & Steam, there are no other platforms included in this.
This is related to files that shouldn't be in your game folders. If you delete the content folder and then verify your files, you will have the correct PAK files and have no issues.