Symerty on custome made imported bones

Hello ;] this is my first post here, and im a new blender user (playing around with it for few months).
After years on max its kinda difficult ^^".

Ok so i have a issue with imported bipedal armature that needs to be adjusted for a character but the bone names are already set and it doesn’t work with blender X-Axis Mirror :frowning: now they are something like this “character:LeftArm” for it to work would need to be “character:Arm_Left” or “character:Arm_L” right XD?
This naming convention need to be preserved since already majority of characters and animations in game use.

Can easily adjust the symmetry without editing the naming of hierarchy?