I am confused. Are you asking if Xara can edit a PDF form that was sent to you or are you trying to make a editable form for a web site?
If it's the first one, then I have been using Xara for years to edit PDFs. Unless the form is just a picture that has been made into a PDF, then you should have no problem.

Some forms, like Docusign where you need to use their service to modify and sign you will not be able to modify their PDFs.

Ray