It's a paraphrase in some parts, but the text is the same as any English translation you read. Certainly nothing heretical has been inserted.
FYI, the Psalter is one of the parts of the OT most in error in the King James version of the OT. Even the D-R (translation of the OT into English from the Latin Vulgate), is not free from error. The only canonical Holy Scripture is the LXX and the only canonical translation into English of the LXX that I know of is that published by the Holy Transfiguration Monastery in Boston, MA. If your paraphrase is not from that, how do I know it's not filled with heresies? Who's to say?