Schedule: modify a value defined by a key in a value table

Hello everyone,
I’ve been working on a subject for some time, the idea is to export a door schedule on revit to automatically make an Excel spreadsheet with particular cell formats. I’ve managed to do so, but now I need to generate the opposite effect ; import the Excel spreadsheet to modify the schedule on Revit. The problem I’m having is that some of the values of some of my parameters are conditioned by a key schedule integrated into my project template. I started working on a test function that would enable me to understand how to modify the values in my schedule. Here, for example, I’m trying to modify all the cells in my “_FINITION_PORTES” column corresponding to the types of finish on my doors.

def modify_door_finish():
    # This function modifies the door finish parameter for all doors in the active view.
    # Get the current Revit document
    doc = revit.doc
    # Get the active view
    view = revit.active_view
    # Define the parameter name to be modified
    parameter_name = "_FINITION_PORTE"  # Name of the finish parameter
    # Define the new value to be set in the finish parameter
    new_value = "Finition thermolaquée pour porte métallique"
    # Collect all doors in the document
    doors = FilteredElementCollector(doc).OfCategory(BuiltInCategory.OST_Doors).WhereElementIsNotElementType().ToElements()
    # Start a Revit transaction to group all parameter modifications
    with Transaction(doc, "Modify Door Finishes") as transaction:
        # Iterate through each door in the collection
        for door in doors:
            # Check if the parameter exists on the door element
            door_finish_parameter = door.LookupParameter(parameter_name)
            if door_finish_parameter:
                # Set the new value to the parameter
        # Commit the transaction to apply the changes
    # Display a message box indicating successful completion
    UI.TaskDialog.Show("Success", "Modifications completed successfully")

When I execute my code, I don’t get any errors, but no changes have been made. However, if I change the parameter to set in my code, to modify the content of another parameter (not conditioned by a key schedule), no problem, everything works correctly. I don’t know if it’s possible to operate directly in a schedule on a value conditioned by a key schedule (even if the new value is already contained in the key schedule).
Does anyone here have any ideas?