The "Japan" article in the numisdoc was last edited in 2015 and it says the last era was the "平成" or "Heisei" era, but since then there has been a new emperor and a start of a new era which is not listed. It is the "令和" or "Reiwa" era meaning peace and harmony (or something along the lines of that). This era started when the last emperor Akihito abdicated on May 1st 2019. Then his son Naruhito became the 126th emperor; and the new era Reiwa was announced. All i suggest is that you add the Reiwa era and put it as 2019-. Then for the Heisei era put it as 1989-2019 instead of 1989-.
-George