she is shooting 120 grain stainless steel points made specially for koreans and some select others and not for sale over here
all world class archers select an arrow in this order: point weight (heaviest possible) spine to tune point weight (slightly stiff), poundage adjustment to tune arrow. No one shoots a sub maximum point weight unless a sub 40lbs holding weight female recurve or sub 46lbs gent and there aint many of them around at this level.
so the answer to why tungsten: pureley point weight, any protection to the shaft is secondary, the foc is better with dense material so a perceived bonus
OB when u get a set of x10's bare in mind that a set of 28.5 (nothing out the back) X10 450's with tungsten 120grain points was right on the limit of tune (shade wippy) out of a 47lbs on fingers set up I was working with today so start in the 430 bracket and appreciate it wont be quick but it will be massiveley more consistant than the 520 spine aces you have been using