I assure you the Israel Postal Service can read English better than the US PS or Royal Mail can read Hebrew. I would write everything in English with Kiryat/Qiryat/Qiriat being all equally valid spellings. Also, put Israel in large on the last line to be doubly sure.
“but if someone at the PO doesn’t know, they can Google it with the zip code and get it in Hebrew or English” – I can’t imagine they sit there looking up zip codes on google.
(Don’t do what a friend of mine did once and put ‘Zionist Occupied Palestine’ as the country.)