I don't understand why you are using /assist target and /target and NOT using /assist focus ? Seems to me to be a bit more flexible.

My examples--


"Big Dots"
/assist focus
/stopmacro [noharm]
/castsequence reset=15/combat/target Immolate, Curse of Agony, Corruption

"Dots"
/assist focus
/stopmacro [noharm]
/castsequence reset=combat/target Curse of Agony, Corruption


"Shadow Bolt"
/assist focus
/cast Shadow Bolt


"Set Focus"
/focus [target=party1,nodead][target=party2,nodead][target=party3,nodead][target=party4,nodead][target=party5,exists][target=player]
/target focus


"Follow"
/follow focus