There’s been no change as yet to how we’re able to handle additional fonts on iPad, because the Qt framework that Dorico depends upon doesn’t support the latest APIs for fonts on iOS. It’s not clear whether or when they will support these APIs, and unfortunately that makes it very difficult for us to support additional fonts.
In the specific case of the Notation Express templates, one option would be for us to install all of the fonts used by those templates in Dorico for iPad’s own distribution. We’re considering this.