I'm wondering what's involved and or if the old wallets are even accessible anymore. It was the original wallet version from the first year of bitcoins launch. Seed phrase and then the other password and so on.
Seed phrase isn't available at that time or even today as BIP39 wasn't implemented to BitcoinCore.
It wasn't even HD at that time either, it's all random private keys so your older backups might contain outdated number of keys than the one you've used
beforeafter you saved that backup.
The old wallet files might work because AFAIK devs have been keeping backwards compatibility but if you stumbled upon a problem,
there are available tools like "
pywallet" to read/extract the keys from your wallet.