To replicate Amsnag's functionality would require a much deeper and more difficult hack to beat Amtrak's security and independently invoke that internal Amtrak API to get a JSON object which the hacker could consume to get the data. Although a few months ago a member here apparently had successfully done that, I have not heard anything more about it.
Unfortunately I have not made any more progress- The hang up is still in making Amtrak consistently accept requests, as they tend to block you after fetching JSON a few times.