Theme Icon Fonts problem - just show letters no icons

Hi ...Please take a look,
is this normal? since I only have few icons to use on the editor.

I think this is related to my problems of missing some icons on the page

how to fix it to work on my fixer theme :expressionless: I feel the irony.
and is there any options to changes the icon with 'icomoon' which is already on the upfront/font folder? or anything that just put on the simple custom CSS.

Thank you!