I’m proposing a fix with https://github.com/sailfishos/mkcal/pull/27
The issue comes from the fact that the event is defined with RDATE only, starting in January. The events are not showing in the calendar, because, the incidence is actually loaded only when swiping to January, and then the ranges for the other months are already flagged as loaded in nemo-qml-plugin-calendar, so the occurrences for these ranges are not recomputed (and thus not displayed). The alarms are set because the event actually exists in the database, but are not shown due to the bug.