“Suggestions wanted” - it’s a specific phrase meaning the Emperor is looking for suggestions. In the printed version, however, it’s been replaced with “right wrongs”. Now that I’m thinking, it probably has to do with the fact that specific sides of the box were supposed to correspond to specific phrases, and this relationship is known and fixed. There might have been a mistake in the original version, maybe one day I’ll check if that’s how it is.

“Add more firewood” - the situation here is a spin on the historical conflict between Lai Junchen and Zhou Xing. After Lai Junchen has been ordered to investigate Zhou Xing, he had a meal with him and asked what to do if a suspect refuses to confess. Zhou Xing suggested getting a large jar, heating it and putting the suspect inside.

Lai Junchen immediately had a jar brought over, set up the fires around it and told Zhou Xing he was ordered to investigate him, “So, please, get in the jar.” Zhou Xing immediately confessed.

Now, the phrase “invite a gentleman into a jar” can be used to mean “to have something backfire on someone”, “give one a taste of their own medicine”.