I'm sure there will more functions added to the official API, but one way, if anyone is interested, is to use functions to pass information from the event sheet to the script and vice versa.
You can use globalThis.c3_callFunction("FunctionName", []); //The array is the function parameters.
You can also get a hold of the full addon sdk, but I think that defeats the purpose of a nice clean API for accessing everything and can lead to issues if the inner workings change.
I'm sure this functionality and a lot more will be added to the official API, but in the meantime you play around with using functions.