I would think both would be a problem. Rattling around could cause problems as the shifting of the pins changes the geometry of the FCG parts. This will change the pull from shot to shot. If there is enough change in the geometry, the FCG will become unreliable. I don't know how much movement is needed to cause problems.
How well the spring legs hold the pins in place I don't know. But if the holes are enlarged and out of round, the pins will shift and possibly in such a way that the springs could push the pins out.
The more the pins move around, the greater the wear on the pin holes.
Opening up the pin holes to accept a hardened press in steel shoulder bushing would be an ideal repair for this problem if it's not cost prohibitive.
The KNS pins will stop the pins from walking and reduce the amount of play and geometry change. A drop in trigger would be better, but more costly.
What I would do in your place is install the KNS pins as a temporary repair and begin the SBR paperwork on a replacement lower

