I have tried to find a Mod Pack that Fixes the TWAL Shadow, but the Only one I found change a load of ther things too. So i made my own and uploaded it so you can use it too.
This is kind of two Mod Packs in one. You can use the MPS Install Script which will change the TWAL to have no shadow. The downside of this is that you can't use the shadows to create caves and things.
Or you can use the modified Data File which will add the Tall Wall into your editor. The Tall Wall is a TWAL with no shadow. It doesn't replace anything!