The unl regex excludes the ")" character:
unl_regex = re.compile(r"""\bunl:[^`'")]+""")
Why is that? It would not be unusual to have a node whose headline includes one. For instance: regex (test2).
Currently a node whose headline includes the character cannot be found by Leo's unl: handler. I would like to remove this restriction unless there is a good reason for it. (The regex is in leoGlobals.py).