Okay so the clash points that you are collecting are not scaled to the Revit model units.
This is the location of the instance:
And this is the plane origin that you are trying to reorient to:
I changed the python node to reorient based on the location of the instance itself but use the X and Y axis directions from the plane:
Also added data type checks. Change the python code to this:
import clr
clr.AddReference('System.Core')
clr.AddReference('RhinoInside.Revit')
clr.AddReference('RevitAPI')
clr.AddReference('RevitAPIUI')
from System import Enum
import rhinoscriptsyntax as rs
import Rhino
import RhinoInside
import Grasshopper
from RhinoInside.Revit import Revit, Convert
from Autodesk.Revit import DB
doc = Revit.ActiveDBDocument
clr.ImportExtensions(RhinoInside.Revit)
if isinstance(I, DB.FamilyInstance) and isinstance(L, Rhino.Geometry.Plane):
t = DB.Transaction(doc, "Align Instance")
t.Start()
I.Pinned = False
I.SetTransform(I.Location.Point, L.XAxis.ToHost(), L.YAxis.ToHost())
I.Pinned = True
t.Commit()
Here is proof of work: