Good on you for standing by your partner and finding ways to accommodate what is undoubtedly a challenging lifestyle. Unfortunately That 0 equilibrium person as you call it is exclusively what Fromsoft painstakingly centers their design decisions around. Sadly most media cannot be tailor made for any one person even if that ideal sounds enticing on paper.

As an example there are locations in Souls games where altering statistics or even player damage would be meaningless because the predicament requires balancing on a narrow ledge while enemies fire massive arrows at you. Being blind in this location would make it absolutely impossible to beat no matter what crutches were granted to the player. Multiply this single instance with many more moments like this and an easier mode cannot alleviate the core design principles without overhauling the game itself.

That investment would be 100× more significant than any kind of accessibility feature a dev team could implement. FromSoftware put everything into meticulously crafting an experience that caters to the mantra "difficult but fair" in order to grant as many players possible the euphoria of overcoming a challenging obstacle. Sadly not all gamers play from that 0 equilibrium and in many cases cannot remotely be adequately accommodated.