Nice that you got it to work!
If you wanted to combine the lists in python you could have used zip()
for view,curves in zip(views,curvelist):
#Create curveloop
loop = CurveLoop()
for c in curves:
loop.Append(c.ToRevitType())
#Set cropregion in Transaction
TransactionManager.Instance.EnsureInTransaction(doc)
view.CropBoxActive = True
view.GetCropRegionShapeManager().SetCropShape(loop)
outputlist.append(view)
TransactionManager.Instance.TransactionTaskDone()
OUT = outputlist