I realize that I could just test it, but I thought that I would ask to shortcut either my pain or someone else’s that comes after me. The question on subsitutions is.
Do substitutions support hierarchical structure. Meaning do I need to flatten my JSON.
Just a note for lurkers on the thread, you have to pass a value in for the value int he template, for example, if I have {{contact.first_name}} in my template, but do not but that in the substitutions array, it will throw an error.