https://files.catbox.moe/xbmhfq.mp4

I took the ruby lazuli song and put the japanese and korean on the left and right audio channels for comparison. Korean big red dork is pretty similar to japanese big red dork. Korean Tamaki isn't super close to the original, since Suzuki Anna has a very distinct sound when she sings.
I think they usually try to get as close as possible to the original voice acting, but I sort of like it when they take liberties. They did it a little bit in RL and to this day, I still think korean nth color is superior to the original.