Hi Marcus,
Its always helpful to include the Revit / Rhino about info(your image was helpful in this regard but sometimes the details matter). Thanks
There are number of ways to sort, if you break out this question without the Revit components you can get some additional (shorter) methods in the Grasshopper Forum.
Here is a quick go at that groups by the Z, then sorts by the Y.
RE_RhinoInRevit Test V2.gh (89.2 KB)