Not sure my word is going to mean much, but yes, we do indeed plant these trees :) We also publish regular tree updates to make the impact more visible (latest one is here https://www.youtube.com/watch?v=FeBhY5m9npE&) and just now some of my colleagues are in Indonesia: https://www.facebook.com/ecosia/videos/1056643057857650/

We also use a ODK-backed system for monitoring, where our partners on the ground fill in surveys about the trees they planted.