There is no one here who has even a minimal clue why your problem with korean Mnemonic exists... And as there is no professional team and no funds to pay one, there is actually zero chance that someone will update the tool to exctract the private key... (And even I - who invested some of my spare time to adapt the Tool for ECA - was not really a person responsible for Electra OR personally concerned (had no ECA on mobile wallet, and (at the time of the Snapshot) - no ECA at all). So, for me, it was just a personal hobby to try to find a solution for people with ECA on the mobile wallet. It worked for most - that it didn't work for you is unfortunate.

So, if your really interested in solving that problem, you might have to do it yourself, or at least find a person that is competent to do it...