CG File Explorer 17 で覗いてたら別のlocale.iniを発見
CS機用っぽくて日本語用[REGIONALIZATION_jpn_jp]が既に書かれてた

[REGIONALIZATION_jpn_jp]
INTEGER_FORMAT = DDDD
FLOAT_FORMAT = DDDD_DOT_DD
DATE_SHORT_FORMAT = YYYY_SLASH_MM_SLASH_DD
DATE_LONG_FORMAT = MONTH_COMMA_SPACE_DD_SPACE_YYYY
TIME_FORMAT = HH_COLON_MM_COLON_SS
LENGTH_UNIT_FORMAT = METRIC
WEIGHT_UNIT_FORMAT = METRIC
PERCENT_FORMAT = H_PERCENT
FOUR_CHARACTER_LANGUAGE_ENCODING = jaJP
MINUTE_FORMAT = MINUTE_QUOTE
DEFAULT_NATIONAL_TEAM = 1369
DEFAULT_FAVOURITE_TEAM = 1
DEFAULT_LEAGUE = 13
CURRENCY_TYPE = DOLLARS
CURRENCY_FORMAT_DOLLARS = CURRENCY_SIGN_FIGURE
CURRENCY_FORMAT_EUROS = CURRENCY_SIGN_FIGURE
CURRENCY_FORMAT_POUNDS = CURRENCY_SIGN_FIGURE