Both .epsp and .ai5 files are actually PostScript images, typical exports of graphics from Adobe software (Illustrator or Photoshop) for printing on PostScript based printers or to act as exchange formats to another software. It is actually possible to import these files back and even export again if you truly want that. In any case, Adobe Photoshop or Illustrator are probably your best options here.
Updated: August 9, 2023