@Hinoiri ..
I don't know about the other actors BUT CFY voice was I am 100% sure NOT DUBBED.
That's him .. I can pick him in a crowd from his voice, after having stuffed myself with CFY shows, YT clips, him singing .. rewatched L&P 3 times (and plan to again). That's HIM.
Also Song Yi Ren - I have heard her in other dramas .. unless they used the EXACT same voice actor for her everywhere.
And Wang He Di??
Ummm... that wasn't his voice??
I've heard that (not so great .. little squeaky .. slightly higher pitched) in his other dramas AND YT clips (interviews .. BTS).
What he lacks in 'voice quality' he makes up with his acting SKILL