Can't translate strings properly to Hebrew and Arabic

[אורי]

I can't translate strings such as "2 weeks" to Hebrew and Arabic properly. There is a word in Hebrew and a word in Arabic for 2 weeks, but I get an error message "The expression '%d' is not present in the translation" in Transifex and also msgfmt -vc django.po raises exceptions. In some languages, with some plural forms, such as n == 1 or n == 2, we don't need %d to be present in the translation. Also "1 week" can be written in words "one week", also in Hebrew, and I think it's a better translation than "1 week". I also think English can use "one week" instead of "1 week" (but in English, there is the issue of capital letters).