I am playing SGE and I offered to swap spots with my co-healer. Tbh, that GCD shield there is very unnecessary. Get who you can with it while you are at the wall. It is def much more important that everyone catches plenary/caress. Also, if this helps, there is a tech where you can get kera on mystery magic and on LoJ if you Kera early. For me, it is 2 GCD's after the second hit of the tank buster but you can also just kera at 5 sec on the pre-pull timer and then kera as soon as it is off CD (my way of making sure that my kera is 25 sec into the fight without needing to guess). That extra 10% makes getting people healthy for wave cannon much comfier. This timing also allows for an extra kera if you do it again as soon as it is off CD to catch Grav 1 and also catch DTT + LoJ.