Yes, that would be really cool, to have ultra big armis in multiplayer matches like a GoW dm. Sadly i have tried chance population in savefile, but is not find as exact value, must be calculated from the total farms you have.
Did you hit the max then save the map, then sav the map with just a few units? Compare the files it will narrow down then value. It might be easier to scan the memory location and remove the 004 and you now have the offset.
Some value is most likely increasing or as decreasing. So I would recommend you scan for changed and not changed in memory since you have no clue what the true value is.
Cheat Engine
1. Make units scan for Unknown Value
2. Kill a unit next scan for changed value.
3. Kill a unit, walk around, build a different unit, scan for unchanged value. (This will filter alot of stuff you don't need.)
4. Repeat the steps over and over. You will most likely find the location.
Edit: the other map editors war2xed for example has no limit on the units you can put down but playing the map then the exe will not display all the units. I only hope the unit cap limit is not hard coded like 64x64 - 128x128 (map size limit).