Seems like your map lists pre-historic ring forts, not castles?
I'm not sure what the 'official' definition of a castle is, but I personally wouldn't consider a crannóg or something like Dún Aonghasa a castle. Nor would I consider a stand alone tower house a castle, although they might (along with gate lodges and great houses), sometimes be colloquially referred to as castles.
Surely a castle is a fortified building, specific to the middle ages. Wikipedia agrees - https://en.wikipedia.org/wiki/Castle
Which would put the number of Anglo-Norman castles in Ireland much lower, probably something around 100.