My first Smart Search was for your example, "What happened at the Council of Nicea?" The results were great! However, when I used the alternative spelling "Nicaea," it gave me different results (depending on how the resource spelled the word). For example, with "Nicea", The Moody Handbook of Theology was included in the list. With "Nicaea", it wasn't.
Hopefully this kind of spelling variation issue can be taken into account, and Smart Search will continue to improve and become the robust tool it promises to be.