sp1der,
I just tested JFBConnect using the "Normal Registration" flow where a user can select their own username. A 1-character username will not work. Joomla requires all username's to be at least 2 characters, and we do not circumvent that.
If you're seeing the ability to create usernames with one character, than something else is wrong. I do understand that 2 character usernames may still be too short, but that's not something we can fix since it's a Joomla check, not us. If you can create 1-character usernames using JFBConnect, it seems like something else on your site is allowing that, and I wouldn't know what.
use the fb login button and jfbconnect will retrieve the name from fb on the next page.
choose the register option and amend the firstname or lastname follow with clicking the submit button.
compare registered full name in joomla with what you had amend before clicking the submit button.
I'm not following this and/or can't recreate what your saying here.
I think it'd be best if you start a new topic with responses to the above as this is very off-topic of the original post. We'll gladly keep helping you in the new topic though.
Thanks,
Alex