something I am trying for my healing is this

set up say 1 as the button for your "FrostyBubble"

each mage gets a different macro

/cast [nomod] FrostyBubble
/cast [mod:Ctrl, nomod:ALT] FrostyBubble
/cast [mod:ALT, nomod:CTRL] FrostyBubble
/cast [mod:SHIFT] FrostyBubble
/cast [mod:CTRL, mod:ALT] FrostyBubble

and make sure keyclone is set to pass all 5 variants.