What’s not working?
Make sure you follow the steps in the video link, if you haven’t watched it yet.
Miss a step, it probably won’t work. (Keep pausing video if you need to and complete each step as you watch
As to the double cello, I think EW allows you to reassign keyswitches. Never done that though, but it might be a solution. As long as your keyswitches don’t conflict with each other and there are open keys to assign still.
(I don’t believe I cued up the video to the exact part that will help but it’s a little further along I think)