Ok, I had same output : command failed. (I used one debug node)
I don't understand why I must to use three debug node on this case !!
After that, I changed file "adc.py" on dist-package on line 57 : self, address = 0x08 (before value was 0x04) on usr/local/lib/python2.7 and now, I have some value on debug node. (one debug node again)
I already do this modification on dist-package for python3.7 but not for python2.7.
So that's a good news. Now if I try with node-red-contrib-capasitive-moisture node, I haven't error on node-red-log but on the debug node I can see : payload : function
My setup : timestamp - trigger node - moisture node - debug node.
