This tool only derives 20 address_index per script type and will only derive 20 more addresses from the last used one.
With that, it will not work since he needs his key/address from around 50,000 address_index and the lower index are probably unused.

Other tools may have higher gap limit but I'm pretty sure that nothing will set it to more than 50,000 by default.
So it has to be derived from a specific range like the example in my previous reply.

The problem here is he didn't shared the code of that "script" that he mentioned.
Because it could be unintentionally using a different derivation path that Electrum uses.