Use command (not runtime command):
cmds.matchTransform() # not cmds.MatchTransform()
And second argument must also be an object, rather than object’s position.
So, in your code it should be jnt (joint), not joint_position:
cmds.matchTransform(groups, jnt) # not cmds.MatchTransform(groups, joint_position)
There are additional flags that you could use with this command, depending on what you actually need to match (pivots, position, rotation, scale, etc.), so you might wanna take a look at it’s docs.
P.S. “L_R” seems like rather strange prefix…
If intention was to list left and right fingers’ joints, which are named something like “L_Finger1”, “L_Finger2”, “R_Finger1”, "R_Finger2’, or in similar manner, first line of your code won’t find anything (or will find joints named “L_Ring1”, “L_Ring2”, if they exist, because these names start with “L_R”), so you won’t enter the loop.
Probably you meant something like:
FJoints = cmds.ls('L_*', type='joint') # list joints starting with "L_" (left side)
FJoints.extend(cmds.ls('R_*', type='joint')) # add to the list joints starting with "R_" (right side)