[...]
Gave it a shot, Btcrecover does not support dumping legacy core wallets. At least that is what the script told me once I had it up.
Could you please share the specific error message? I seem to remember that this worked in older versions of BTCRecovery. So I would be surprised if the feature has been removed.
You could otherwise contact support with the specific error message via github-issues:
https://github.com/3rdIteration/btcrecover/issues You might get some more hints here what else you could try?