I very much doubt you are going to find a digital piano with a lighter touch than your Roland Go.
As I said prior I had a Yamaha P series but this has a much heavier action than a Roland Go and hence I do not think anything in the Yamaha or Casio digital piano range will be lighter than the Go.
I now have a Numa Compact 2X (digital piano and drawbar organ) which has a semi weighted keybed, it is a bit lighter than Yamaha which is graded in its weighting. They also produce the Numa Compact which is just a digital piano that may work for you.
If it does not then I suggest that you forget a digital piano and go for an Arranger, such as a Yamaha PSR E463 or Korg EK50, yes they only have 61 keys but they have synth action keybeds which are very much lighter than a digital piano with hammer action.