so their time of filming is wrong, the elderly have probably already slept, they should film in the park at the early morning, instead of interviewing the young adults during the night time.
they should find some older people e.g. age 60-70 or even 80, because Taiwan was captured by Japanese during their youth or adolescents period. the elderly Taiwanese did not want to die, so they tried hard to learn Japanese that time, so if they were not dead yet, they were around 60, 70 or even 80, then they were highly likely to all know Japanese just too well.