[ Hope I am posting this at the correct Board ].
I have completed 3 map (using Map Editor created by OzoneX). The first 2 map are not really complex and just a way for me to understand more of the map editor. But all in all, I noticed all map play the same. Reasons are ...
[1]. Even you designed a map with complex terrain contour (eg. lots of up and down ground level) but the AI don't take advantages of this to flank enemy.
[2]. The AI design isn't that good. They don't take into account of map environment such as knowing their shot aren't hitting enemy but hitting a wall (with enemy hiding behind the wall).
[3]. Too few type of things on map to make gameplay complex. Such as only Mex and Pgen are all you have.
For item [1] and [2], modders can't do anything about the AI design as it is implemented in the game itself.
But for item [3], maybe modders can fix that. Look to Dragon Dogma Dark Arisen (DDDA) game for ideas. Although this game is an Adventure game but the upgrade system is very good.
I mean, for SCFA game, the upgrade system can change a bit eg. unit's upgrade isn't based on Tech 1, 2 and 3 (which is too simple gameplay as all base on Mex and Pgen found on map). But instead your units must destroy (or kill streak) certain amount of enemy and reclaim it's wreckage to unlock the next upgrade.
Example if you want to upgrade your XYZ big robot from Tech 1 to Tech 2 then you need to send him out for battle. Killing certain amount of enemy (need Engineer to reclaim enemy wreckage) then will unlock the next Tech upgrade for all that type of big robot XYZ.
For most smaller common units, You can still use Mex and Pgen to get economy going to get to next Tech upgrade. But for bigger size robot then can use the DDDA upgrade system which required gamer to kill cerain amount of enemy for that upgrade.
Hope this will make gameplay more interesting.