Maybe I’m not fully understanding this because I’ve never tried to do a direct Houdini to PCG transfer. But I believe I know what’s happening here.
FBXs can’t hold point data, only vertex data. When you export and import it into Unreal, all of that data disappears, and Unreal PCG creates its own point data.
Unfortunately, the static mesh sampler doesn’t have many options for point sampling, and PCG is lacking in ways to sort points like Houdini has. In my opinion, PCG is unfortunately still lackluster in a lot of places when compared to Houdini 
You may have some luck with sorting the vertices in Houdini, then in Unreal/PCG extracting the vertex number and creating points based on the vertices / sorting based on the vertex number.
Good luck with this! Let me know if you need any more help. If you’re able to send over the fbx, I can take a better look on my end.