1. If using ImageTrans desktop for text rendering, you need to change the default font in the project settings.
2. If using the extension to render the text in the browser, you need to add a CSS rule in options like the following: font-family: cursive, sans-serif;

What is shortcut on screen? Do you need a button floating above the image to trigger translation? Is auto translating, which detects image elements and starts translating, not enough? You can open issues here: https://github.com/xulihang/ImageTrans_firefox_extension/issues

Update: added a floating button to translate the image.