Q. As in this critical mageifa (pandemic) days we all daven at home, if someone is used to add his own private prayers for his needs during shemoneesre in English, can he still do so when he davens without a minyan?
A. Shulchan Aruch (O.H. 101: 4) quotes two opinions if one can daven and ask for his own private needs such as for the ill or any other painful situation in his home, in any language he desires when he prays without a minyan, or one should only avoid the Aramean language that the Malachim dislike.
Mishna Berura (ibid. 15) explains that the first opinion maintains, that the angels do not understand any other language besides lashon hakodesh (See Tur O.H. 46 regarding kaddish). However, when one davens with a tzibur, Hashem Himself listens to his prayers and there is no need for the help of the Malachim.
Therefore, Horav Shlomo Miller Shlit’a advises, that if possible one should pray his own tefilos to Hashem in Hebrew when davening at home without a minyan.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a