Slitherine

If I make a global mod with an edited squads file that changes sizes of certain units, say, a normal size 480 men spear unit became a very large 960 men unit, will the exported FOGE battle take the size into consideration and create less units with more men each?

Good question.

The conversion is points based, so as long as you increased the points cost of the modded units appropriately, there would be less of them. (But in proportion to the points cost, not the number of men).

As far as I know there is nothing stopping global mods from working with exported FOGE games.

Try it and see.