December 31, 1914: “The Provisional Executive Committee for general Zionist affairs…announced ‘today’ that the Turkish Post Office has prohibited the use of all languages except Turkish, Arabic, French and German” which will present a problem for Jews writing to Palestine because most of them write in Yiddish, Hebrew and/or Russian. (Mitch Levin)
So, while they may exist, covers mailed to and from Palestine and addressed using Yiddish, Hebrew and Russian are rare.
In 1920, Transjordan was separated and distinctive overprints on postage stamps for the two territories came into use. As Palestine came under the civil administration of the British Mandate of Palestine falling into line with League of Nations rules, the High Commissioner sanctioned stamps (as pictured below) and coins bearing the three official languages of British Mandate Palestine: English, Arab, and Hebrew. Between 1920 and 1923 six such distinctive overprints were issued: four produced in Jerusalem, two in London. (Wikipedia)
Shown here is a 2 milliemes postage stamp printed prior to 1920, while the British Egyptian Expeditionary Force (E.E.F.) occupied Palestine and then overprinted in 1920 in Arabic, English and Hebrew: