Hide GUI text from non-resource pack players

I have made a GUI which works using font characters in the title. (negative space, gui overlay, negative space, normal text)
Is there any characters which, despite the font being set and the player not having it, will display nothing to those players? (e.g would be nothing, nothing, nothing, normal text
It is for a plugin which explicitly supports non-RP players also, I have a "ui design" which is hidden by a combination of CustomModelData and the overlay for resource pack players to smoothly support both, but this is a hurdle I can't work out a way past