18 years later, Shixun was acting strange, making them think to have failed in raising him to a good heir. What did Shixun hide from them?

Sounds a little strangely worded.
'making them think they had failed in raising him to be a good heir.' The major issue is the 'raising him to a good heir', it just sounds odd either get rid of 'him to' making it 'making them think they have failed in raising a good heir' or add a be such as 'causing them to think they have failed in raising him to be a good heir.'

the capital of han dynasty wasn't beijing but it's okay because historical !!!
can't wait for this haha

oh wow, you chose your title based on what i showed you! haha, good luck with this~ hunhan ftw ^^

seems interesting!