If you have access to a Unix/Linux/*nix command line, change to the plugin directory and issue the following shell command:
grep add_shortcode *.php
Essentially, you are looking for all occurrences of when/where a new short code is added to WordPress.
The first argument to add_shortcodes is the shortcode string itself. The second argument is the name of the function that WordPress should call, when that shortcode is parsed.