This story makes me doubt if I really know English

That’s SAT vocabulary baby! Lol

I tried Google and got:
"Timorous parsimony" refers to the cautious or hesitant application of the principle of parsimony, which suggests choosing the simplest explanation that fits the evidence.
WTF KIND OF ANSWER IS THAT??? I'm even more confused now than when I typed it in!

So a bureaucrat is basically somebody in the government who cares more about the “procedural correctness more than the needs of the people - for example a senator of a state that believes in pro life and will ignore the fact a 10yr old girl was raped or molested and still makes her go thru with having a baby instead of getting an abortion.

Now there were 2 principles being referenced 1) Primogeniture and 2) Parsimony. Primogeniture is basically when inheritance goes to the 1st born child. Parsimony is the principle where the most simple explanation is probably what actually happened - which typically applies to a behavioral issue, medical diagnosis, changes in evolution, or in this case a legal outcome . Example of primogeniture in law - the punishment must fit the crime. You wouldn’t sentence someone to death who’s only going to jail for not paying their taxes - that punishment is typically reserved for murders. The word timorous literally means fear.

So putting timorous primogeniture together in how they meant it in the context of that panel was - Yeonjo’s father who was a government official believed that inheritance was clear cut and couldn’t be argued because the people feared the government - which is what the government as a whole relied on. It was a system he taught to his sons and villainized Hye-Ryang when he murdered his father for treason… because in Yeonjo’s eyes his father tirelessly (indefatigable) fought for what was right. The vocabulary can be confusing if you’re not familiar with the definitions but you have to apply the meaning of the words to what happened in the story to understand because there’s multiple definitions.

Hope that kind of helps!

I thought it might be something along these lines, but you have to admitted that for a person whose mother tongue is not English it's hard and confusing, not the type of words you stumble upon normally

I thought parsimony was stinginess? And timorous means fear/anxiety. So basically, this dude believes bloodlines/inheritance and hesitant spending are constructs of good governance