Recovering my old bitcoin wallet
I think the least &quot;intense&quot; option here would be to look up each of the wallet addresses from your ckey items on a node (i.e. blockchain.info blockchair.com btc.com etc) to see which ones have any value in them.
Once you have a list of the wallet addresses that are &quot;worth recovering,&quot; you will need to take those ckey items' encrypted private keys (possibly along with data from the mkey item) to attempt to manually decrypt/recover your private keys to those wallets.
If you're experienced with programming, you could read through the code from the version of bitcoin core you used in 2014/2015 to figure out how it was encoded. Otherwise, you may need to find an experienced programmer you can trust, to help here.
As a post-note:
Have you tried re-compiling a copy of that older version of bitcoin core on a sandbox system? It's just a try, but maybe the file just got caught by a reverse-compatibility issue!