Copying the saves over doesn't work as the images in them aren't present in 6.2, you get a black screen telling you the image isn't there if its prior to chapter 6.You don't have to!
All you need to do is, either start the ep6 u2b with pathmaker, and define a few variable, or copy your saves from ep5 u4 to te /game folder of ep6 u2b, and try to load it.
Alternatively you can find, and try my edited files, but at the moment you can only play with it up to ep6 u1. I'll definitely need a few days to work my way through the ep6 u2b, and try to eliminate any bugs.
Pathmaker doesn't allow me to go to use my old saves it just creates a new save point with whatever I input at the start of ch6 or the most recent content. Its a long time since 5.4 which was my last save and theres no way I remember every choice I made. For example, the very first choice is who won in the arcade - I have a path for both so I could see all the content and I have no idea now which path I ultimately took. It feels like a LONG time ago.
Ultimately, the saves should work in 6.2 - it shouldn't need you to recreate a fake save by inputting a lot of data that may or may not be right. Coding hasn't changed heavily its just some very odd choices by the dev to remove images etc.
I never made it through the pathmaker so no idea if it re-enables the WT.