Hi! Im very new to modding and have poked around the sims XML and python files for a solid dozen hours or so. I cannot for the life of me figure out how to make x happen after y occurs. For example, When an aspiration is completed, a global variable increases. I am familiar with Python and was just planning on making a script mod but I cant figure out the event listeners for Sims 4.

Events are typically tracked as "Objectives" or "Situation Goals". You may be able to create one of these, or you can look at how they work in order to create your own systems.