The only problem I can recall with Ys 4 is that there's atleast one song that isn't on the Ys 4 Perfect Collections. It's the very last song that's used for the final cinema where the "lady" is telling the children about Adol's adventures. The begining portion of it inludes voice acting, so, you'd need to find an alternate way to do that scene. Now that I think about it, there might be a "version" of that song with no voices on the Perfect Collection, but it's different.
Ok, just check it, it's there, but different. My suggestion would be to use the Perfect Collection one, it might be the same length as the original. When the time comes, I might be able to play around with the original & the Perfect Collection versions to get the right length for the song. There might be a few others you'll need taken from the Perfection Collections, I have all 3(though, I only have a real cd of the 1st disc, the other 2 are cd'rs) so I can help with this, especially in regards to preparing the cinema tracks. I also still have my all my takes for Dr. Flair, & I believe all the lines for Lilia my wife did, & all the lines my friend Jessica did for Bami. I was also gonna try for the Narrator, but, by the time I started working on that, the original project fell apart. But hit me up when you need those tracks, & I'll try to take some time & go over all the cinema tracks & see if there's any altering needed for them to fit in the original scenes, etc.