Dunno about “the last update” or the current state in each region but as far as I know the default search engine in FireFox has varied over the years and has always depended what country you’re in.
Baidu, Yandex and Yahoo are / have been the default in some countries. They made Bing the default for “1%” of users in a bunch of major countries recently to test the waters (and didn’t take it further than that).
Google blocks traffic from Chinese IP addresses as a protest against censorship there, so nobody has Google as the default in that country.