My understanding is that, for Sephardic Jews, all anniversaries (including Yahrzeit) that occurred on Adar, are observed on Adar II (Adar sheni) on leap years. This is different from the Ashkenazi custom as is briefly explained here:
It would be great to
1.) For such dates, add a note/warning at the top of the page.
2.) Eventually, offer a setting on this page to switch to Sephardic version.
Customer support service by UserEcho