Okay, so you have data which is great, but if you look at the documentation you will notice that it expects an array and that is an object.
I think at this point your issues are data structure so. you may need to massage how the rsvp event comes back to format it in a way that appendvalueswrapper() expects.
You may have to simplify that data even more then just changing it to an array. That I’m not sure about as I haven’t played with this package much but given that the docs show a very simple array being passed, I’m not sure how complex an array it can handle.