Iroha is an older Japanese poem with deep connections to Japanese culture and religion. There are a number of different versions – the original cannot be read by the vast majority of modern Japanese readers. It has been translated in a number of languages but the translations lose much of the nuance and meaning.

Although its scent still lingers on
  the form of a flower has scattered away
For whom will the glory
  of this world remain unchanged?
Arriving today at the yonder side
  of the deep mountains of evanescent existence
We shall never allow ourselves to drift away
  intoxicated, in the world of shallow dreams. 

Abe, Ryuichi (1999). The Weaving of Mantra: Kûkai and the Construction of Esoteric Buddhist Discourse. Columbia University Press. ISBN 0-231-11286-6.

There are a number of potential aspects of trust in this RLE:

  • Differences between the original text and the modern Japanese version
  • Differences between the two Japanese versions and English translation
  • Whether or not a non-religious person trusts Buddist translations of the text
  • Whether or not a Japanese researcher trusts research on the poem from non-Japanese sources
  • Different interpretations of the literary elements of the text