Since the meeting we have continued to implement Duolingo with our classes. A part-time teacher in the department has returned from a long illness, and she is also keen on using this tool, and has in fact implemented its use with her classes.
All the teachers are on board with the project. From here I see it will be necessary to monitor their use of the tool with the classes, to make sure it they don't forget to remind their students to be using it, and in fact encourage them to use some class time on it.
In one of my classes, one Year 8 student, after failing a test, was given a Duolingo target of spending at least 20 minutes a day on it. To begin with, despite being a good student, he hardly spent any time on it. After a couple of weeks he came up to me and said, "I like Duolingo now, I've decided to treat it as a game". At which point I thought "Yes, that's the point, and why it is effective", but I said, "Great, I hope you can make your target now". However, this did make me realise that some students see it as schoolwork, rather than the gamified learning experience it really is, and that it's important to get the students to see it as a game, and not work.