Unless you are desperate for a paddling from bedges, you shouldn't open three threads for the same question. This thread can be merged with
your original question and
your first solution.
Using the search term "kill counter" in the first place would have turned up
Kendo's Casualty Reports.
To have the number displayed, edit the 'End' trigger for the mission. Give it a timeout of a couple of seconds, eg. 3,3,3 and enter something like the following in the Activation line
titletext [format ["%1 kills", west_casualties], "plain", 1]
Replace
west-casualties with whatever variable you are using for the counting.
As suggested by bedges, you could have found an example of this use of the
format command in the COMREF.