So I'm quite new to Houdini and I'm trying to solve a problem that I haven't seen yet in any online examples. I need to take a list of grid coordinates, and build a room outline from that.

The coordinates are just as simple as:
0,0,0
0,1,0
0,2,0
etc

Now this part I've got a pretty good handle on (I think). I'm taking that, generating a poly that matches and I get the basic room outline. The problem comes in the next steps.
I need to grab the various surfaces (walls, floors, ceiling, etc) so they can later be uv'ed and textured.
I also need to round the corners according to some very specific art-driven rules. It's not enough to just round the corners. The corners need to be rounded very specifically based off of the corner's direction. I've included a zip that contains a sample file that shows my attempts so far and some pictures that explain the problem probably a lot better than I can.

Add to this the fact that we need to find a way to bridge gaps with prop bridges, detect where stairs should go and many other issues… These can come later, however. Right now I'm mainly concerned with the room outline.

As I said, I'm pretty new to Houdini and I've made a few attempts and have a few other ideas to try, but I'm hoping somebody can save me a lot of wasted time by pointing me in the right direction.

Any help would be much appreciated.