It's pretty frustrating. Scaling, faceting, and/or polyreducing each input helps but the meshes still come out incorrect, just less so.

Is there another work around? Maybe a custom HDK sop?

If your scenario allows it, you could convert geometry into VDB: VDB from Polygons / VDB Fracture or VDB Compose and Convert VDB to come back to polygons… lots of polygons. Not always feasible, but still helpful.

With Vdb you can crank up resolution high (like 1K^3) making volumes very accurate.

thanks but I need to keep things low poly