bbcode.html file is currently ignored and not the default way of editing bbcode templates. This is mainly due to the requirements of a template_bitfield and bbcode_bitfield. These should not exists. The contents of bbcode.html or eventually bbcode.twig should be whats cached and not based on a generated string of bits. ludacris!
This makes it impossible for theme authors/admins to make changes to the styling of bbcodes without knowledge of php and bitfields.