Long story short, a game that is striving to be as mechanically deep and complex as dark souls will always be handicapped by buttons without proper feedback. What makes DS and other soulsborne games so great is that the deaths are always your fault, and not the controls or some sort of forced moment (And when the latter happens in the game, it is always considered a big mistake on the developer FromSoftware’s part).
I don’t want to sound like I’m being mean, but I feel like a dark souls player would play this and ultimately die because the touch buttons failed them. And that is a rage quit moment.
I would have to say that you would need to make the game easier to allow for a margin of error, but that isn’t fixing the problem, and instead making a compromise for a system that isn’t ideal.
That being said, I’m talking from a pedantic armchair game design perspective, and I doubt the majority of the players would really mind that much. The Legend of Zelda: Skyward Sword had something similar, which raised your minimum heard count from 3 to 6 to compensate for the motion controls which are not 100% accurate like a button, and that game sold gangbusters!!
Long story short, I really like the amount of work you put into this, but I feel like mobile might not be the best place to put it. Some sort of portable device might be a better idea. Maybe even a portable device that is coming out soon which has a really cheap dev kit made by a certain Japanese console manufacturer 