It is possible, but it'd take some major rewriting of the mission generation portions of the mod. We would certainly like more variety, it'll just take me some time to test and work out.
The way races and missions are chosen right now are done by what is known as the "mission table" - at the beginning of a campaign, the game engine makes a list of possible missions for every region. Each month, one mission (meaning a set of craft activity done by a single race) is picked from the table, run, and removed from the table. The start of the game is coded to run a Cultist mission automatically in the region of your first base, the remaining is RNG-based. This is the part we'd be editing, deciding how the table gets populated at the beginning of the game, what actually appears on your end is only mildly up to us.
On top of this there are also mission scripts that run independently of the table, producing the monthly terror mission as well as the side operations for the marines or the side missions for the guard. We can use this method to run more of the mission generation, but it'd end up feeling, well, "scripted".