I am afraid currently Aspose.Pdf for .NET does not support the feature to individually set the border style for form fields. However for the sake of correction, I have logged this requirement as PDFNEWNET-39317. We will further look into the details of this requirement and will keep you posted on the status of correction. Please be patient and spare us little time. We are sorry for this inconvenience.
The issues you have found earlier (filed as ) have been fixed in this update. This message was posted using BugNotificationTool from Downloads module by MuzammilKhan