Counting how many rows contain chinese in mixed value dataset using python
That should be feasible using some more python and pandas features:
- errors can be caught when you wrap the detect in your own function and return None (or what you prefer) instead of a language code
- results of the detect can be added to the df and counted, filtered, you name it. 

def mydetect(txt):
    try:
        return detect(txt)
    except:
        return None


Pandas allows you to add the results to a second column of the dataframe, but I do not have the command handy at the moment, please check a tutorial.
Then you can filter the dataset or count occurences of a language. 

You can also limit the except clause to certain errors if you think that would make more sense.