On better chances of obtaining MIB commander..
Yeah, I know! I'm thinking of adding some new missions featuring the Commander. Ideas welcome (but not in this thread, please).
.. a very obvious answer here would be increasing the chance of MIB outpost instead or in addition. Its chances are only 3 % starting month 28 and it requires MIB Activities research (by researching non-agent). You could increase the chances significantly, even to, say 15 %.
Alternatively, you could increase the chances only slightly (say, to 6-8 %) yet create a second mission script that would trigger with STR_MIB_IDENTITY or STR_MIB_OBJECTIVE. Researching that requires obtaining MIB coordinator, essentially, which you can get for example from MIB Stealth Bombers. Then the player is nearing the phase where they would like to see MIB commander soon. Then the chance for MIB outpost could be even higher, say 20 %.
Out of about a dozen campaigns I have played (though I usually stop just before or after MIB commander or arbiter because I get bored), so far MIB outpost has never spawned for me. It would be nice to get it much more frequently.