RN most likely stands for resistor network, and these would be there to match the line impendance and/or help terminate the line and prevent ringing and under/overshoots from getting too big. At this frequency the resistor values have to very low, so while maybe these are not 0ohm, you should be able to get the board to work again by just bridging the damaged pack afer removing the cracked leftovers. Very short wires to nearby vias might just work too but forget about routing a separate wire from the CPU socket to the chipset/RAM slots.

I've repaired one XP mobo where someone cut 2 traces with a screwdriver stab. I had no components to replace, "just" to fix two traces with 2-3mm of thin copper wire, and I've had a bit more room to work with if only barely. So... good luck with this one.

I have an A7V333 and a multimeter, but not a lot of spare time 🙁