> `removedPropertyNames` does not match the actual `removedProperties` :)
And this parameter is an array of strings, `?Array.<!string>`, no?

Fixed.

About `setProperties` and `removedProperties`: I think they are much more specific than `metadata` and `removedMetadataNames`, and would set a good convention for other similar classes of fields -- style properties for example.

Nothing wrong with previously-webodf-internal naming patterns showing up in the Editor API as long as they are used consistently.