Prophecy, for one, is at first open to the unique interpratation of the translator, which can give words or sequences whole new meanings as the meanings of words alter and society views change. For instance, someone translating a prophecy just after the Breaking would have a different view on the role of the DR than someone born 1000 years later. Someone alive just after would have an understandably bleak view, but there would be some positives in there as well as he's just saved them all, however, the person translating a prophecy 1000 years later would put an entirely different spin on it, as the DR is now viewed as a thing of nightmares.

Secondly, we've seen through out the series that these kind of messages contain a huge use of symbolism. Foretellings, Dreams, Prophecies all use symbolism as it almost seems easier for the seer (for want of a better word) to understand. For instance, we would never take the Dream of Rand splitting the Westlands into two with a sword literally. He's not big enough for this to work. We know it means something other than what we see. It makes it easier for the WOs to understand. We've also seen this in a number of Egwene's Dreams: we don't expect Mat to actually dice with the DO, or Rand to build a physical wall between himself and women who can channel.

But it's not just dreams we see this in. In KOD we see both Mat and Perrin referred to by symblos. Mat the fox and Perrin the wolf king. Fair enough, these are quite apt terms for them, but they're not exactly accurate are they? They suit a purpose, they make the information easier to understand.

With this in mind, looking at the Seanchan prophecy, it would be easy for Ishmael to corrupt a prophecy discussing the seat of someone's power: from where their power resides, to THE seat of power: the Crystal Throne. This would make the Seanchan attitude to the DR fraught with power struggles from the beginning, making something that seems to need to be done (the Alliance) difficult.