PS: i did use dimensions from an existing skin which is 2286x2000 in @2x

Because you're using selection-mode. Which is layered above the text while having a normal blend mode. It's also anchored to the bottom left corner of the asset. So nothing on the left side of it will show.

In the old skinning method:

1. selection-mode should only be a silhouette of the top part (with a few exceptions for small details).
2. The actual colors should be placed on mode-{x}-small.
   
   1. This file has an additive blend mode. Meaning it's colors will show up properly over a black background, while the white text will be fully readable since it's impossible to add any value to fully white text
3. selection-mode shouldn't also extend this far up and to the left. Since the file is layered above the text layer, it will just cover it. If you want to see the proper way of doing it, check out how I did it in this skin.

I also recommend you try using the new songselect-top and songselect-bottom files. They make skinning much easier.
Wiki link for reference. (scroll down a bit)

additional advice if you do intend to use songselect-top and songselect-bottom

1. As per wiki says, songselect-top will repeat pixels at the right side from a certain point. If you want any decoration on that side, preserve them on selection-mode instead.
2. As per wiki says (again), the height of songselect-bottom matters because it will prevent you from interacting with the song selection. I'd suggest skinning them only when you want the editor song selection to look pretty too, and even then mind the height still.
3. Those sprites, unlike the usual selection-mode strat, will go under the elements instead of over it, so if you still want to do something like the custom tabs at the top right, reserve them for the good ol selection-mode.