I remember i could do this before if my memory serves, and part of the reason why i took a long hiatus from this game is the inability to remap my controller on PC.
I remember using my bumper for guard breaking for respond time reasons. Is there a reason why they took it out?
Since i am unaware of why i cannot remap my controller, My feed back is to have this option again.
You should actually look into the options of the game before you post sth like that. It is there under advanced controls -> controller layouts. And btw if you would have brought you to it you could have found out that from the very beginning the community found ways to rebind controls since feb 2017 so that you could use any custom controller you wanted (for me PS1, custom PS3 and later PS4 which worked of course right of the bat as it is one of the officially supported).
Anyhow by season 4 or 5 I think they implemented the mentioned ability to change your controller setup ingame officially. You can switch button functions and modify your sticks deadzones. However these are very basic options. It was overall quite a lazy work. What is still missing there is the ability to bind multiple functions to one key as well as defining and differences of button presses with actions.
In steam big picture there are several options more to play with. You can differtiate between inguard mode functions out of guard mode, as well as menu. Great stuff but has its drawbacks too. I for one had issues with the camera stick sensitivity and with the quick chat menu in which one function would never be assigned to any button like the others. :/
Had fun function which allowed me to press R2 to run and when I would release it I would go into guard mode and vice verca. Tried to even differentiate and have target swap on a light tap ond said button while on a press down and hold exit guard mode again and start running. Binding one button for zone attack was also a piece of cake.