Usually I run around with 3-4 "daily" targeting macros on current action bar; two or three aggros I will probably encounter plus one grinding mob. Which can change even few times in a single session.
Now, yes, there's macro editor but
$>tmacros.py olmo kipesta,kipucka,najabis far simpler.
Problem is obviously that editing keys_<char>.xml isn't enough. File has to be reloaded. Based on limited testing this already happens on session change (zoning) but not always. It seems like only when region changes (e.g. Forest -> Desert) but not when zoning within a region.
So it's not like anything needs to be coded in except clicking depicted button manually triggering same procedure.