Can it be done without a "Rosetta Stone"?

[-JKP-]

My feeling is that

• if the text is meaningful and at least somewhat narrative in a few places,
  
• if the images relate to the text,
  
• if the text is sufficiently long,
  
• if a reasonable estimate of the date of creation can be determined (within a century or so), and
  
• if the system is reasonably consistent (this is a pretty big condition)
  

then I believe it's possible to figure it out without a Rosetta stone.