Generally speaking:
1. Find the variable for the event in question. This can be done by looking at screens.rpy. Using "Level One", one of the most recent Molly events as an example, you'll find that the variable is "mollyspring1".
2. Next you need to find where that event is triggered. To do so, you need to look for the line "jump mollyspring1". You can find this in chap4hub.rpy.
3. The line before this will usually be where you find the event requirements. The label this all falls under is important as well. In this case, the preceding line is "if day == 7 and saracamp2 == True and mollyspring1 == False:" and the label is "morningch4". This tells us that the event will be triggered on a Sunday ("day == 7) morning if you've already seen the event "I've Been Thinking About Leaving This Place" (saracamp2 == True) and you haven't seen "Level One" yet ("mollyspring1 == False").
