how that in much proof of affliction the abundance of their joy and their deep poverty abounded unto the riches of their liberality.

In the terrible ordeal they suffered, their abundant joy and deep poverty overflowed into rich generosity.

because in much trial of tribulation the abundance of their joy, and their deep poverty, did abound to the riches of their liberality;

that in a great trial of affliction the abundance of their joy and their deep poverty has abounded to the riches of their [free-hearted] liberality.