PDF form fields salesforce api

We have been working with the Salesforce ESL App and are noticing unusual behaviors with PDF Form fields and how the data is layered onto the PDF. Is this behavior the same when utilizing REST or any other API with ESL? What are most peoples experiences with using PDF Form fields? Should the formatting work? How does one interact with a grouped checkbox - i.e. 5 checkboxes but only 1 can be checked at a time? I am seeing numbers not line up.. and checkboxes require editing the PDF before I can use it. Any thoughts?