Found this as a solution/hack. I was hoping gdb module had a demangler. I'll wait for a better answer.

import subprocess

def demangle(name):
    args = ['c++filt', name]
    pipe = subprocess.Popen(args, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
    stdout, _ = pipe.communicate()
    return stdout[:-1].decode("utf-8")