This isn't a transpilation error, it's a feature of arrow functions. The arrow function automatically sets the context of the function body to the contexts here it was created, in this case the callback to Meteor.publish. This prevents Meteor from rebinding the context of your listener function.
From the Meteor publish docs:
Inside the function, this is the publish handler object
If you want things to work properly you will need to use the "old-school" function syntax to allow Meteor to set the context properly.
