Quote:
the standard is to use family name first in Japanese and in romanji on names prior to the Meiji Restoration, but family name second when writing in romanji post WWII.
No. The official Japanese standard is now to use the surname-name order in official documents. This was announced (I think) in September 2019 and came into force on 1st January 2020. This will no doubt spread to other areas of life in due course. In fact, it has already been working its way through since 2000 when a government advisory body first made the recommendation.
The thinking behind it can be found if you search on something like ローマ字の名前表記姓→名」の順に, but to put it in a nutshell, the government felt that the west should learn to respect the diversity in the languages of the world, having noted in particular that the Chinese and Korean governments do not kowtow to the west in the matter of names.
The western academic world has long been moving in the same direction, in the same way that it abandoned Wade-Giles for pinyin (Sun Zi instea dof Sun Tsu, for example).
The problem came about in Meiji times when Japanese wanted to be hip by copying the west. Western organisations such as newspapers compounded the problem by copying them. Chinese people came up with a better solution: two names rather than two orders. One name is their own original; the other is a western first name tagged in front of their own surname (a go example is Yin Mingming = Stephanie Yin). Koreans created a different kind of problem by not only adopting western order but also mispronouncing their own names (Lee Changho instead of Yi Ch'ang-ho, which derives from yi becoming ri if you were to read the original Korean name in western order, i.e. Ch'ang-ho Yi has to become Changho Ri/Li [lambdacism applies], or the equivalent for Syngman Rhee).
There are many good reasons for following the oriental order, but I'll leave them as exercise for the reader.
The orientals need to take advice, too, incidentally. Western go players, even professionals registered with their organisations, are routinely referred to by their "Christian" names as if these were surnames. E.g. Catalin instead of Taranu in Japan, or 자카첸코마리야 = Zakharchenko Mariya rather than Mariya Z.; 雷蒙麦克 [Léimēng Màikè; or just Maike] for Michael Redmond in China.
But even there there are caveats. One is that oriental usage varies. Another important one is that people in Europe often use the surname-name order.
In short, it's very messy subject, and there's much, much more in similar vein.
My advice is:
1. Follow the oriental order/customs
2. Follow the western experts but not news organisations
3. Don't ever trust Wikipedia or SL