"signifying the divine post-diluvian Remission and Reconciliation of the Terrible"
'Honi soit qui mal y pense' is the motto of the English chivalric Order of the Garter. It can be translated from the French as 'let him who thinks ill there be shamed', or reinterpreted as 'evil be to him who evil thinks'. In this paragraph, Mr Rosencreutz explains that his meeting with Fevvers on May eve is not to be of a sexual nature. The date, and the relative position of the stars and moon, signify Christian forgiveness of human sin following Noah's Flood, when sinners were removed from the Earth and humanity entered a temporary remission from its former misdeeds.
'Yoni' is the Sanskrit word for female genitalia. By replacing the word for 'shame' in the above quote with the word 'yoni', Rosencreutz condemns those who think evil not to shame, but to involvement with female sexuality which to him is terrible. This replacement is not his (or Carter's) own, but appears in Jennings' The Rosicrucians with 'yoni' as the central discus, rosy cross or feminine flower - which in this text was not the root of evil which it appears to Rosencreutz.