You'll notice that the definitions that you offered for perpetual and constant have massive functional overlap, and regular probably also meant roughly what you suggested constant means. If he's really outlining distinct qualities, then this is a poor translation because it sounds ridiculous and the distinctness of the qualities is unclear but, having read a fair amount of Hitler's writing and speeches (albeit in translation), it's my inclination to say he's just being redundant here, especially given the other comment about Hitler being a poor writer.

The criticism goes on:

Mannoni's comments are similar to those made by Ralph Manheim, who made the first English-language translation in 1943. Manheim wrote in the foreword to the edition "Where Hitler's formulations challenge the reader's credulity I have quoted the German original in the notes." This evaluation of the poor quality of Hitler's prose and his inability to express his opinions coherently was shared by William S. Schlamm, who reviewed Manheim's translation in The New York Times, writing that "there was not the faintest similarity to a thought and barely a trace of language."[41]