Currently I can only suggest a few things:
1) FusionFall help/support should continue to help you with that since it's probably
a website/account problem due to your account being so old. (A BETA account.)
I've heard that accounts that have been inactive for 6 months or more, get deleted but
I am not sure how true this is.
2) Check your Spam/Trash/Bin/Junk folder in your email. (And other emails you own.)
3) Try every single email you've had access to, you never know,
one of them may have been the one you actually associated with the account. (Also check the spam folder, etc.)
4) When you made the FusionFall or Cartoon Network account, what age did you put
as your age? If you put 12 years or under, you may have had to provide a 'parent's email'
to allow you access to the '13+ feature' of free chat. (Not selecting words to communicate in the game
but actual typing.)
So it could be that 'parent's email' account you used. (If it was fake, and you don't remember the email,
well that option is gone. Especially if you put an age of 13 years or older in that case only one email is associated
with your CN or FF account.)
5) Check your inbox for REALLY OLD FusionFall messages like a welcome
email or a parent's permission email or something.
Just try searching FusionFall in your email inbox. (Those emails may be as old as from 2008!
is why I don't recommend checking page by page in your inbox.
Emails like those may provide an answer, perhaps even a password reset link.
6) If you remember the email you used but it was fake, make that account
and see if you can do the 'I forgot my password' thing again.
Hope something helps.
(Most likely, trying to remember the email associated with your account is probably your best bet.)