This should also be incorporated in a comprehensine text tool, not just in watermark.
For an example of this feature, see Picture Window Pro 8.
PWP8 includes macros to extract file properties and exif data to build the text block, such as: camera model, f stop, shutter speed, focal length, ISO, description…
Refer to document “transformation”, page 222. I come to DxO P Picture Window Pro 8, and it handles text very comprehensively. Refer to text transformation, page 222.