No one knew where to start. Wike says here_ https://wiki.guildwars2.com/wiki/Defeat_the_Priests_of_Balthazar_powering_up_the_Forged_cannonades,_and_then_destroy_the_cannonades
We did one event, no follow up was in sight at the specified location. After 30 mins, the Commander and most others left to do Caledon Forest for the dailies instead.
My GW2 content charts: (1) LWS 4, (2) PoF , (3) Personal story (pre-Claw Island/Orr) , (4) LWS 2 , (5) HoT, (6) Orr campaign , (7) LWS 3