Given a particular definition of "new" - I'm not a speaker of Te Reo myself, but have lived my entire life in Māori majority communities (the supermarket in my wife's ancestral hometown appears to have NO internal signage in English), have worked on research projects on the health and status of the language, and have many friends who are L1 speakers. The use of the macron is not less than 20 years old, and even before that existed as a doubled spelling of the vowels. Since some variant of macronisation has been a widespread feature of Māori orthography for at least half of my half-century, with some attestations going back further still, I'm loathe to call it "an entirely new concept"