I was confused by the handwriting and some of the words in the document, but after you translated, it made more sense.
Apparently, it's not Plato, but Platon (Rozhdestvensky) - name of the Christian Orthodox archbishop of Aleutian and North American Diocese from 1907 to 1914. Eventually, he held the title of the Metropolitan Bishop of Canada and US - the highest ranked official of the Russian Orthodox church in the region. https://orthodoxwiki.org/Platon_(Rozhdestvensky)_of_New_York
Interesting letter, but likely off-topic for this group.