Even if it might be a late response, I found a solution for your specific problem, to obtain the intersection from two curves. However, I unfortunately dont have a solution why clr.Reference[SOMETHING] does not work under CPython in general.
#! python3
import clr
clr.AddReference('RevitAPI')
from Autodesk.Revit.DB import *
import logging
logging.getLogger()
doc = __revit__.ActiveUIDocument.Document
# Example Code to retrieve all grid lines in the current project
allGridElems = FilteredElementCollector(doc).OfCategory(BuiltInCategory.OST_Grids).WhereElementIsNotElementType().ToElements()
curve1 = allGridElems[0].Curve
curve2 = allGridElems[30].Curve
results = IntersectionResultArray()
cmt_or_result_tuple = curve1.Intersect(curve2, results)
print(cmt_or_result_tuple) # when both curves overlap the result will be a tuple of (SetComparisonResult.Overlap, IntersectionResultArray), otherwise it will be just the 'SetComparisonResult.Overlap'
if(cmt_or_result_tuple[0] == 8):
r = cmt_or_result_tuple[1] # when overlap access the result in the tuple (SetComparisonResult.Overlap, IntersectionResultArray)
intersection_point = r.get_Item(0) # there's an undocumented method named 'get_Item'. I used print(dir(r)) to inspect the element
print(intersection_point) # in internal revit units 'feet' convert if necessary