You can try using https://github.com/WheteThunger/ParentedEntityRenderFix.
Configure this to include the piano, lantern, etc., at a minimum:
{
"EnabledEntities": [
"piano.deployed",
"lantern.deployed"
]
}
This is a workaround, and ymmv. There is probably a more thorough and accurate description, but from your perspective, it impacts any plugin that builds an object using multiple entities and/or those that generally aren't meant to move. Sadly, these are some of my favorite plugins. It didn't used to be a problem but began as part of Facepunch's efforts to improve game performance a couple of years ago. I've even had issues with plugins I'm working on that only consist of one object, but one that is generally grounded and not supposed to fly.