Everyone is wondering what happens when you fly through a widely dispersed ash cloud and its after effects.
Here is link to the USGS study on exactly that - the aftermath of Mt. Pinatubo in 1991 (bigger eruption than this one)
Casadevall
Flying for CX at the time I remember Manila was closed for 2 weeks while the eruption was on and the ash scraped off the RWYs afterwards (55nm downwind from the Volcano).
Other than that there were various re-routes on HKG-AUS vv and in the (very busy) South China Sea.
There was some damage to aeroplanes but mostly very minor (see above report). One IFSD was reported in the 18 encounters during the aftermath.