Question

Why do deleted events appear in the event list after the project is rebuilt?

Answer

From the UI perspective, the deleted event names do appear in the list after the deletion intentionally. 

It was done because the deletion of events, potentially, might break any view in a schema, or if you apply any filter where other events could depend on the deleted event. The current implementation was made to still show deleted events in the list, but contain zero timelines.

Therefore, if you build a filter or schema, it will not break anything but you will see it with 0 timelines