Edit Tier and Benefit metadata

The API docs for Benefit show a lot of metadata that can be associated with it: including description, app_external_id, and app_meta. However, I can’t find how to edit those properties on patreon.com. If I make a custom benefit, I can only set the title. I would like to be able to also set some of these other fields, including a private metadata field that I can use programmatically.

I would also like to do the same for Tier: associate some private metadata so that I can query it programmatically from my app integration.