SUMMARY You can set subscript or superscript for a part of text and save and it will work, but you cannot set it to the whole text. STEPS TO REPRODUCE 1. Create a text shape, open the editor. 2. Select whole text. 3. Go to Format -> Superscript. 4. Observe text in the rich text editor changing to superscript. 5. Select all and press Save. OBSERVED RESULT Text on the canvas doesn't change. EXPECTED RESULT Text on the canvas should change to superscript. SOFTWARE/OS VERSIONS Krita 4.3.0 Linux Mint 19.3 ADDITIONAL INFORMATION If you just select a part of text and set it to superscript or subscript, it will work. So it's not rendering that's wrong here.
I can confirm this It is possible to set the entire text to superscript or subscript by using the svg editor: Have one normal letter followed by super/subscript characters created in the rich text editor then save and close. Open for editing and use the svg editor to remove that one letter, then Save. The entire text will then be in superscript. However, if you edit again and use the rich text editor then it goes back to 'normal' text.