She pulled out the classic "I am a poor victim", regardless of the fact that she was the one who have choosed to marry Ruve and become the Emperess. While fully knowing that she couldn't even read their langage mind you. She complaint a lot and say things like "How can you expect me to be as good as she was? Give me time ! I am already doing my best studying"... Right. Because the citizens can wait until you finally get a grip and try to catch up to the 4 years you did nothing. She did a very poor job, even changing Tia's policies that were working and doing so became hated by the servants of the Palace that are sick of having to deal with her nonsensical policies and having their stand of living lowered because of her mistakes (it's because of that that in the second timeline she don't hesitate to punish them harshly).
Personally, I wonder how Jieun would be doing after the unjust execution of Tia. She had been neglecting her empress duties and responsibilities and Tia had been doing all her work. Tia was good at her work while jieun was ignorant of what it meant to be an empress.
Would she continue to neglect her duties or do a terrible job? and would the people realise how useless she is as an empress? Would she lead the empire to ruin by neglecting her duties?
Please respond, I really want to hear what you think could have happened.