adding support for Coptic letters is pretty recent
in the past the official way to write Coptic was to use the Greek alphabet
but the Greek alphabet lakes the demotic letters ϣ ϥ ϧ ϩ ϫ ϭ ϯ
so those letters were included, therefore any font can display them
but problem is, current Greek alphabet is different than the old one adopted by Copts
in the recently the they finally decided to dedicate independent space for Coptic's alphabet
(except of course the demotic letters because they had their space already)
so any font can any of the letters above, but the remaining alphabet is expected to be supported soon
in the future any font should be able to display Coptic letters properly
