I have experience working with multibit wallets. Maybe I can help.
The wallet itself is lost. Dave Bitcoin has been working on it since early 2014, bruteforce of the entire range up to 10 characters has been attempted.
At one point, KeychainX found a false positive using the words i gave him, but it was just that - a false positive.
My only remaining options at this point are to handle this like solving the puzzles, but with my own wallet

Pollard Kangaroo approach is for the know private key range and for the best, within 125 bit range and of course since you have the Multibit wallet handy all you have to do is "Once you located the files, if you have access to an old multibit app on you computer you need to import the wallet and export the private keys to a new wallet. If you do not have a copy of Multibit, you can use OpenSSL together with your password to decrypt the files and recover the keys."
You need the password to export them. I still have the wallet open every single day since then.
I just keep looking at what value i've missed out on

If you have the .key or .wallet file, your best option is brute force, if they haven't been able to help you with brute force 10 characters? (or that's what I understood), it's simple, programmer error.
maybe it's an encryption problem, some software have had problems logging in when updates are applied, or special characters that are interpreted differently.