Several things struck me about the list. One is that it does not go back that far. There are certainly written records predating this, but many or most of those might have been lost over time. For example, the Cascadia Subduction Zone quake of 1700 created a tsunami on the West Coast of the United States. It was of course not recorded, but Japan did record what is called an orphan tsunami, one that isn't associated with a local quake.
The number of deaths associated with these events are certainly estimates. Even the 2004 Sumatra tsunami with its large number of deaths is surely an estimate--even in this modern day. All the bodies from Japan's tsunami will not be found. People will be listed as missing and presumed dead.
The last item I'd like to comment on is the wave heights that are mentioned. Remember that these are not open ocean wave heights. Even big tsunamis in the open ocean may be only a few inches tall. It is when they run up against a land mass that they build in power and force. The particular underwater features of the coastline can also concentrate the force and size of the wave in particular areas.
