There is no downside to changing them, but try and do it when you create them then leave them along, renaming them from the form doesn’t do a refactor operation yet, so if you are using the veriable a lot of places in code (like listener implementations) that could become a problem.
I always change the names to something useful. For example nameLabel, nameCheckBox, nameTextField, okButton, cancelButton, browseButton. I always append the name of the Swing type after the name of what the control does, sometimes it leads to really long names, but I prefer more descrip code over short names that are hard to decode. I hate seeing things like rsvButton, or lktCheckBox… I have no idea what that means if it’s not my code and just makes my life harder as a developer. So from time to time I’ll have something like userPaidInDollarsCheckBox, but atleast the developer that comes behind me to work on that code knows exactly what it does 😉