Is there a up-to-date script for converting from a Woltlab Burning Board 2.3.3 to a smf?
You'll find the latest available converter for Burning Boards 2 in the download section:
http://www.simplemachines.org/download/?converters
Will it work with a 2.3.6 board too?
I would assume so, but I figure you can do a test run of trying to convert to SMF and see. It will certainly prompt with any errors. Be sure to backup your source DB just in case.
http://support.simplemachines.org/converter_request.php