The transistors on the node boards are through hole, just like every other transistor so not sure why they are hard to repair.
I have had 2 flipper coil transistors desolder them selves from node boards and the coil also shorted. Not sure which happened first. New transistor and coil fixed the issue. Stern replaced both quickly.
I have a lot of Spike games out and some with 50k+ games and no node board failures, yet. I did have a CPU on one of my GOT fail and was replaced quickly by Stern.