Needs some clairification but here is my best guess based on what you are saying.

I presume you are complaining about the fact that cycling through objects list with D-left and D-right includes things like other players, objects, npcs, etc...
D-up and D-down is your party list only.
L1 + D-up and -down is your enemy list only.

I am guessing you want to change D-left and -right to cycle the enemy list only. This can be partially achieved with target filters while the weapon is drawn. While it is not perfect because mobs move around causing their d-left and -right order to change; making it hard to get that one enemy you want to provoke. And yes, pressing L1+d-up / -down certainly less convenient than just d-left / -right.

Have I described your issue correctly?