Question regarding new UI for editing font-size presets

In this latest version of ‘Gutenberg’ plugin, there is a new UI for adding/editing font-size presets, I am able to add a custom font size and rename it, but I can’t edit/change the slug name.
The new custom font size is renamed to ‘Huge’, but I can’t change the slug name.
It’s set to ‘–wp–preset–font-size–custom-1’, I want it to be ‘–wp–preset–font-size–huge’ or something similar (such as ‘–wp–preset–font-size–custom-huge’).

Thanks!