It does. The problem is that the "marionetteScriptFinished" is associated to the sandbox commandid that created it (the "context")

In the previous case, the "marionetteScriptFinished" was called withing the context of "register" instead of "wait", hence it did nothing because it was assumed that the call was not for the "wait". So I have to pass it as a callback when I do the "wait"