Is there a way to trigger events?

[pezhetairoi]

actually. There is a place you can trigger it, or so it seems. I go to /data/world/maps/campaign/imperial_campaign/descr_events. I believe, for example, you will see something like 'Plague in Thessalonica 14 winter', which means year 14, winter, which corresponds to turn 28. So just change the one that says 'Gaius Marius: A New Man' and see if it works. Try changing it to turn 2 and mode one of your cities to huge city with imperial palace to see if it works before changing it to your desired date. If it works, hooray. If it doesn't, it's just another unimplemented CA initiative.

But a word on it working: I succeeded in delaying the Thessalonica plague (an issue close to my heart since I was playing Macedon) as long as I wanted it, but the catch is you probably'll have to restart the campaign.