Adobe Sign API Form Field Calculation

I have 2 issues with Adobe Sign API with the forms library hosted on my website. 

So once I import the xml file either through local machine or third party API the form will ONLY prefill fields that are 1 to 1 direct field names from the xml file. If I need to do any custom calculations it will not work in the preview (that my webpage generates) unless I click on a field and input some data hit enter and then the calculations work (in preview only) but once it is sent to the customer the custom calculation fields show up as blank fields again.

How can I get fields to do custom calculations if they do not have a field that is 1 to 1 from the xml file that is imported.