Thank you for your kind words, Elegant Totality. The reason why MyFacebook Connect automatically linked your Facebook ID to your MyBB account and MyTwitter Connect created a new account with a strange email filled in is the following: the latter is capable of retrieving the user's Facebook email and check it against the MyBB one. If there's a match, the account is automatically linked (aka "attached") onto it.
Instead, MyTwitter Connect isn't capable of fetching the user's Twitter email due to their API restrictions. So, MyTwitter Connect generates a fictional email combining the user's Twitter ID (18468074) and the board's name, lowercase and without spaces (thefellowshipdiscussionforums) dot com. This is used when the Fast Registration option is set to on (instant registration) and it's there to prevent the datahandler throwing a "email missing" error. It's just a placeholder, basically.
However, you can link your admin account to your Twitter account by using the linking feature present in your User Control Panel.