Thank you for your comment Neko

It has to be viewed on the spiritual plane as it confronts the reality of what we are before our Creator 
We the laity have not seen the original attempt by sister Faustina , we can assume that it is a childlike reflection of the vision she saw, distorted and incomplete, revealing (reflecting) all her human failings, we must remember that she set about this painting with singular pure intent, her actions were acted out in Trust, with confidence, the reality of her attempt is a lesson to all of us, as we venerate (Look upon) this broken distorted image, a reflection before God of our inner self. (Failings/Sinfulness) 

I hope this will help too enlighten you understand.
Sincerely
kevin your brother
In Christ