Comments in parentheses are a feature of MIME, and have nothing to do with delivery of e-mail: those comments are not valid in the envelope header as parsed by SMTP. (Put another way, there is no "the RFC": there are multiple RFCs used for different purposes and which have different rules.) MIME certainly has no relevance to your address book, and if your structured address book database is attempting to parse an e-mail address as if it were inside of either a MIME header or an SMTP envelope, you should absolutely complain: that should be considered a bug :/.

Think about this: one would hope that if you use characters in that field which would normally need to be escaped if used in a MIME message, and that e-mail address were to end up in a MIME message, that the e-mail client would get the unescaped e-mail address from the database and would then escape it correctly--and by "correctly", we mean a different way of escaping it for MIME vs. escaping it for SMTP--the same as we would expect its usage in an HTML page, an argument to a shell script, or a value in an SQL statement, to also be escaped for each specific purpose.