Encontrei uma solução no fórum de discussão do notepad ++:
I managed to get around this by adding all my numbers as a keyword in prefix mode. And then only nest the keyword instead of numbers in my () delimiter. I thought it might potentially be nice to have an option to force numbers to require a preceding whitespace to highlight (excluding the specified prefixes of course). But that may not make any sense.
Isso funcionou como um encanto.