I wanted to use a sneaky block next to a Tinker's smeltery, and I wanted to use seared bricks so it would blend in. But it looks like Tinker's blocks aren't supported yet.

Tinkers smeltery bricks are tile entities. The sneaky blocks intentionally wont work with tile entities to prevent all the misc issues that can cause.

While I am disappointed to hear that, I understand the reasoning for it. I'll figure out a different way to get the effect I was going for.