Полагаю, что этот термин перекочевал в RU из иностранного документа.

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Note added at 27 mins (2020-07-02 15:51:04 GMT)
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E.g.
https://books.google.com.ua/books?id=-142x-gIMsoC&pg=PA50&lp...
Regional Science Association - e: Past President of the Royal Society of ...


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Note added at 35 mins (2020-07-02 15:58:27 GMT)
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https://www.epos.org/know-us/past-epos-presidents
EPOS Past Presidents
https://books.google.com.ua/books?id=t-BjDwAAQBAJ&pg=PA317&l...
Medical
He is a recent past president of the American Academy of Pediatrics, former ... and past president of the Academic (Ambulatory) Pediatric Association.

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Note added at 8 hrs (2020-07-02 23:59:51 GMT)
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https://dictionary.cambridge.org/example/english/past-presid...
Examples of past president
The buildings have gradually been added to with paintings and statues of past presidents and prominent members.
The forums focused on how past presidents and administrations implemented their policy agendas from their first day in office.
In addition, the two most recent past presidents are members of the board.
I am also aware that nothing is past like a past president.


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Note added at 9 hrs (2020-07-03 00:26:28 GMT)
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IMO it does not take a scientist to propose those translation options that immediately come to mind like "ex" or "former", and I do believe that you would have encountered no difficulty in translation at all had there been the term "бывший" in your doc. But, the doc uses "паст" and it makes me sure that it must be translated as "past".