Hi there,
Thank you for reaching out to us!
SimScale supports REVIT format for CAD uploading.
Have you followed the step-by-step instructions from our page on Exporting Revit to SimScale?
To control the facets fully, toggle off Facet split on import and split the STL outside of SimScale by putting it to different STL files and upload everything as a zip file. The files will be translated as solids and the STL-solids will be translated as faces.
Also, have you tried importing the CAD model in other formats? Here is the list of all supported CAD options.