Update :
The dispute was settled in their favor.
They have deleted their twitter account or have changed their name again? I'm not sure which. I did find a protected account with the original name minus the underscore, but it has no discerning links or icons at this time. I have no proof it's the same person, but I'd be cautions of its potential to be the same person.
They do have a youtube account still but it looks like all of the video's were deleted except for 1 posted 1 day ago that just says "you dont know me"
Youtube account : https://www.youtube.com/channel/UCVsXncrGakeKbXe_17V-azw
Included screenshots of the closed dispute and the twitter accounts.
I no longer have access to the DM conversation on twitter. She had not responded past the point screen shot point in my initial post.
I did take the advice of Rendrassa and let them know they hold no rights to the artwork and are not allowed to use it in any regard unless payment is received in full.
All in all, my guess is this is now done. I will be contacting paypal to see if they can offer further assistance but I believe my interaction with the client is now done from this point.