FYI

1966:
JAL hired the first foreign based FAs when they hired FAs in Hong Kong and opened the HKG FA base.

1984: (Dec.)
JAL opened the GRU FA base and hired FAs in Brazil. GRU FA base was closed in Oct. 2010 when JAL terminated Brazil flights.

1988: (March)
JAL opened the SIN FA base.

1988: (April)
JAL opened the LHR and the FRA FA base.

1995: (March)
JAL opened the SHA FA base (now PVG/SHA base).

2008: (April)
JAL inherited the TPE FA bases when JAL acquired Japan Asia Airways. JAA was a subsidiary of JAL which was formed in 1975 when Japan re-established diplomatic relations with mainland China, and JAL could no longer fly to Taipei due to political reasons.

2010: (Dec.)
JAL inherited the BKK FA base when JAL acquired JALways. JALways was a subsidiary of JAL formed in 1990 to operate charter flights and GUM/HNL flights for the JAL mainline. Besides chief FAs who came from JAL, FAs of JALways were hired in Thailand and worked as the BKK based.

2019: (Sept.)
JAL opened MNL FA base and started the FA recruitment in the Philippines, but the pandemic hit and the recruitment in the Philippines was suspended. There is no word at this moment about whether JAL will resume the MNL FA base or not.

I know JAL had Korean speaking FAs way back (like in the '90s) but I could not find any information about this.

Currently, there are about 1000 foreign based FAs at JAL, and about half of them are BKK based. As I mentioned on another thread, there are forign based chief FAs at JAL.