learned of all that had been done

"found out about those letters"

tore his clothes and put on sackcloth and ashes

These acts are signs of severe sadness. AT: "tore his clothes and put on sackcloth and ashes to show his grief" (See: rc://en/ta/man/translate/translate-symaction)

A "province" is a large area into which some countries are divided for the purposes of government. See how you translated this in Esther 1:1.

"the Jews mourned greatly"

"Many of them were on the ground, dressed in sackcloth and sitting in ashes"