Why is "Taisha" written as "general pardon"?
Originally, it was called 大社 (Grand Shrine), but later it's revised to 大赦 (Amnesty).
In Nogi Wakaba wa Yuusha de Aru (Nogi Wakaba is a Hero), the prequel to Washio Sumi wa Yuusha de Aru (Washio Sumi is a Hero) and Yuuki Yuuna wa Yuusha de Aru (Yuki Yuna is a Hero), the organization was originally named 大社 (Grand Shrine).
From ch. 3, pg. 5,

The counter-Vertex organization known as the Taisha (Grand Shrine) had researched the Shinju's power and discovered a scientific and magic method of utilizing it. The outfit was a result of that research. It was the culmination of the Shinju's blessing and the knowledge of mankind.
(Emphasis mine)

From ch. 19 (final chapter), pg. 23,

Hinata already seemed to have a plan in mind as she answered Wakaba's question without any hesitation.

&quot;First, we will rename the Taisha from 'grand shrine' to 'amnesty' as a self-conscious reminder that we have been granted amnesty and live modestly as human beings.&quot;

(Emphasis mine, couldn't quote more than that to avoid heavy spoiler)