Because I created my application before I added ToodleDo sync support, I decided to map my projects to ToodleDo's folders (it's the easiest way to maintain the user's organization on both ToodleDo and my app).
As a result, my projects have a few extra pieces of data (such as a due date and a context). Is there any recommended way of syncing metadata with the folders? Or am I just out of luck?
We don't have a recommended way to sync metadata for folders. We can do metadata for tasks. You might consider making a notebook entry called "MyApplication MetaData" and put the data there and instruct users not to mess with it.
We may add metadata for other objects in a future update to the API.