On screen, granular text formatting tools, accessible to keyframes, expressions, master properties, and mogrts.
There are issues with the current text formatting tools, as we all know. All text properties are buried in a single source text property making it difficult to swap out multi-formatted bits of text in mogrts or with keyframes or expressions, etc.
I think the best way to change this is to add on-screen UI boxes to text. Thin boxes you can use to select different pieces of the text in order to separate characters and/or words, in order to attach properties to them. But the properties would be attached to the boxes, not the words themselves. That way you could swap out a name and the first word in the name would always be one style, while the second word in the name would be another, etc.
Perhaps you could think of it like an extension of the character animator tools. You could even animate a text selection to grow, making characters change their font style in succession. Maybe this would be something that would integrate with text animators easily, making the UI for those a little more intuitive too.
Perhaps instead of "boxes" It could be seen as text property separations by word number or by character number. Then you could keep things in your panel UIs in mogrts if that's easier.