This is not a common situation, it's like an equation where we know 2 variables and the 3rd is unknown.
I need to find password X by knowing the wallet in it's 2 states, both unecrypted and also encrypted with password X. On paper it sounds very do-able to me. We got 2 known parts of a 3 part equation.
That's not at all how AES works. It isn't just an equation. Sure it may sound like that would work, but AES is not some mathematical equation that you can perform such actions on.
What you are describing is called a
Known Plaintext Attack. There are no known Known Plaintext Attacks on AES so what you are asking is currently impossible to do.
On paper it sounds very do-able to me
It is clear that you do not understand cryptography if this sounds doable to you. Because you don't understand cryptography, I would suggest that you don't make such assumptions as they are likely to be wrong.