What do you do with the glyph count? I've never needed it. For storage I need to know the size in bytes. For the GUI I need to know the dimensions of the rendered result.
Caret positioning, selection, etc /if/ you’re implementing text entry yourself - though doing so means accepting the huge amount of work required to support input managers.
In every other case you are 100% correct: you want either the graphical bounds or the number of bytes. The other measures seem of questionable utility to anyone outside of the Unicode library implementation :)
