English to Spanish Social Sciences Names (personal, company) nickname / apodo, diminutivo

The document I am translating is by a Dominican where he talks about different Dominican saints, and jokingly gives each of them a nickname, or short form. I have not found any "official" version for them, so I guess I am free to use whatever sounds best in Spanish.

The next one is Crazy Cathy. I include a whole paragraph to get a better sense of the text:

- Then there’s “Crazy Cathy”, St Catherine of Siena, the only official ‘doctor’ (= theologian-saint) of the Church who was neither a cleric nor a religious, but just an ordinary young woman with whom God did extraordinary things. During her short life of only 33 years Cathy advised popes, princes, priests and people. She converted a mercenary war-lord, a prisoner on death row and thousands of ordinary people. She served the poor and wrote a large volume of influential writings. Cathy had a vision of Christ swapping his heart for hers: from now on his love would warm her body and inspire her words and actions.

God, Cathy taught, is pazzo d’amore – mad or drunk with love for each one of us from all eternity. It is that mad love that brings us into being. And it is told most perfectly when he let his blood spilt for us.

Any suggestions?