OK progress!!
I tried right clicking, going into properties and copying the text etc, still no luck there.
I've had the DLC builder installed this whole time, so I figured I might as well try it now - no use pinning my hopes into the Toolkit if there's another option, and we seemed to have exhausted the possibility of fixing my toolkit issue.
I installed the new WWise, and use the DLC builder - plugged all the information in, made a test build, then a release build. Put that into my CDLC folder and booted up the game to try it. It worked, I had to change tuning on my Bass to match the song, saw album art, loaded it up and had all the notes there. The only snag I had was that the audio started about 3 seconds before the notes started playing, so the timing was a bit off but it all seemed to work!! I'm pretty sure the timing was due to me doing something incorrectly (the add silence before the track step on EOF) but still I'm hugely excited about getting this much closer.
Thank you so much for taking the time to respond here, i'm going to try a new song and start the process again over the next few days and see what I can get. I've spent about 8 hours total going through tutorials, reading steps, making a cheat sheet of notes for the steps, downloading programs and navigating all this stuff that's new to me, and I was getting so let down that I couldn't get the Toolkit to work. Getting the song into the game means I got most of it right, and that's largely due to your help and suggestions. Thank you again, really appreciate your time and help.