IMO 7 days is quite short since he use free (?) API and single-thread software.
Because I gave out hints it's only 2 dates and in 1900-2021 range, to make it easy.
I'm kinda surprised the Etherscan API wasn't rate limiting him. From my experience with APIs, most of them autoban your IP address if you hit them too many times. Sure, they throttle you to a few requests per minute at any rate. That was my original deterrence from making a Blockchair API calling script that running overnight.
The bitcoins still haven't been found yet, apparently, only the ethereum.