import pandas as pd
def exclude_and_assign_above_threshold(series, threshold):
    """
    Splits a pandas Series into two Series based on a threshold, after converting to numeric.
    
    Parameters:
    - series: A pandas Series to split.
    - threshold: The value threshold to split the series.
    
    Returns:
    - below_threshold: A Series of values below or equal to the threshold.
    - above_threshold: A Series of values above the threshold.
    """
    # Convert series to numeric, errors='coerce' will set non-numeric values to NaN
    series_numeric = pd.to_numeric(series, errors='coerce')
    
    below_threshold = series_numeric[series_numeric <= threshold]
    above_threshold = series_numeric[series_numeric > threshold]
    
    return below_threshold, above_threshold