Finds elements based on their Revit Room. This implementation does not rely on the IsPointInRoom() method of the Room Class, so in theory this could be expanded to query against any provided BoundingBoxXYZ.

elements_in_rooms.py

# Load the Python Standard and DesignScript Libraries
import sys
import clr
clr.AddReference('ProtoGeometry')
from Autodesk.DesignScript.Geometry import *

# import doc manager
# Use this to access the hidden RVT DB
clr.AddReference("RevitServices")
import RevitServices
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager

clr.AddReference("RevitAPI")
from Autodesk.Revit.DB import *

doc = DocumentManager.Instance.CurrentDBDocument
uiapp = DocumentManager.Instance.CurrentUIApplication
app = uiapp.Application

def updateParamByName(elementID, paramName, paramValue):
    # We receive ElementID instead of Element object from our Collector.
    # Need to convert to get actual Element reference.
    element = doc.GetElement(elementID)
    
    # GetParameters returns a list.
    # GetParameter does not work.
    # Therefore, we take the first in the list to get what we asked for.
    parameter = element.GetParameters(paramName)
    parameter[0].Set(str(paramValue))

# The inputs to this node will be stored as a list in the IN variables.
dataEnteringNode = IN

objects = []
# Define garbage categories, combine into massive logical filter

# Begin a transaction
TransactionManager.Instance.EnsureInTransaction(doc)
try:

    #* Find all rooms
    # Create FilteredElementCollector for rooms
    all_rooms = FilteredElementCollector(doc).OfCategory(BuiltInCategory.OST_Rooms).WhereElementIsNotElementType().ToElements()
    
    for room in all_rooms:
        #* Get the bounding box of our room
        #* As the room comes from the FEC, we don't need to unwrap it.
        #* We pass "None" to the BoundingBox function so it ignores any View settings
        room_BB = room.get_BoundingBox(None)
        room_name = room.get_Parameter(BuiltInParameter.ROOM_NAME).AsString()
        if room_BB:
            # Convert bounding box to Outline for Filter.
            outln = Outline(room_BB.Min, room_BB.Max)
            bbFilter = BoundingBoxIsInsideFilter(outln)
            
            #? This list can be further clarified with an additional filter to remove other Rooms or garbage objects.
            #? There is some issue on TBC about ToElements(). Need to investigate.
            room_objects = FilteredElementCollector(doc).WherePasses(bbFilter).WhereElementIsNotElementType().WhereElementIsViewIndependent()
            ignored_categories = ["Rooms","Curtain Wall Grids", "Analytical Nodes", "Lines", "<Space Separation>", "<Room Separation>"]
            if room_objects:
                for obj in room_objects:
                    if obj.Category and obj.Category.Name not in ignored_categories:
                        print(obj.Id)
                        updateParamByName(obj.Id, "Comments", room.get_Name())
                        
                        
                        
            else:
                print("Room does not contain any objects. Skipping room.")

        else:
           print("Room does not have a Bounding Box. Skipping room.")
    TransactionManager.Instance.TransactionTaskDone()
except Exception as e:
    print("Exception" + str(e))

# Assign your output to the OUT variable.
OUT = objects