Glad I could help
Actually your question about the explode node taught me something. I didn’t know that you could use the Polysurface.ByJoinedSurfaces node with Polysurfaces, so you can actually skip that part. It makes everything even easier.
The problem in your script was the way you uses the Solid.ByJoinedSurfaces . You need to map that node or it will try to make one big solid out of all the surfaces (no mather what the lacing of the node is set to), as you can see in cases 3 and 4 of the image below.
There is another issue with that node, that I think is a glitch (but maybe there is a reason to it). Even if you map it and get all the separate solids, you sometimes wont be able to import them into revit, as you can see in the case number 2 in the image. If someone can explain that I would be very interested to know what happens there.
That leaves the otpion of extracting solids from polysurfaces , which has always worked fine for me .