An article from Frashogard pointed out by ParsiKhabar, explains why it is incorrect to wish someone “Mubarak” on Pateti.
“On 19th August, we Parsis will celebrate our New Year with traditional gaiety, visiting Agiaries and Atash Behrams, going to see comic theatricals, eating Pulao Dal, sali boti, patra-ni-machhi and wishing one another ‘Pateti Mubarak’. Newspapers will diligently carry small reports on the celebrations, perhaps with a photograph of a happy family posing in front of a fire temple; some will even wish their Parsi readers on the occasion. As the 18th night turns to 19th, mobile phones will buzz with SMS activity revolving around the word Pateti. Thus for a great majority of Parsis and non-Parsis, then, Pateti is a moment of rejoicing that is synonymous with the New Year. But is this all correct?”