do you reload the script once all clients are open and logged in ?

I find this will solve the waiting issue you may be having.

and to remap keys i havent tried it but it would go something like this

This small snippet will remap SHIFT+1 to V

So shift+1 will only go to the first instance of wow open and when you press shift+1 it will send the keypress V to the next instance of wow that is open.

I recently tidied up my code with the wait command so keys dont que when you press them.

[code:1]
WinGet, wowid, List, World of Warcraft

; *** Begin Action Bar sequence ***

~Shift & 1::
IfWinActive, World of Warcraft
{
ControlSend,,{V down}, ahk_id %wowid1%
ControlSend,,{V down}, ahk_id %wowid2%
KeyWait V
ControlSend,,{V up}, ahk_id %wowid1%
ControlSend,,{V up}, ahk_id %wowid2%
return
} [/code:1]