I have made a ffa map with scripted hostile ambient units, I noticed that when playing the map with other people, killing ambient units will give vets (as intended), however when playing solo they do not do so (except if you are playing hunting and they are marked as hunting targets).
Additionally, targeting of ambient units is different. The units have the "if ambient, can be targeted normally" flag. When playing solo, if you click a unit it will only target the single unit, when playing with other people they are targeted as a group (like normal enemy units).
Not too important since its supposed to be played with multiple players, in which case it works as desired, but it would be nice for testing if it was consistent.
It would also be nice if damage to ambient units with the "if ambient, can be targeted normally" flag counted towards damage and kills in the stats. It's kind of annoying to players if they kill 50 units and then their stats say 0 kills, -5 damage.