Pressing Ctrl+, on the code editor opens a configuration panel, but the settings don't get saved so you have to do it every time you open a JS/CSS/Lua script in order to keep your preferences. I request that the settings be saved, or at least be able to be configured via a user script.
I've written a user script that achieves this, but I still wish it was incorporated in the extension itself.
I've pretty much figured this out, but a problem is that you can't translate the settings interface without either (1) modifying the Ace code directly; (2) running a MutationObserver and overwriting the interface every time the panel is opened; or (3) writing a new interface from scratch. The last is probably the most sensible option, but doing so before making the find/replace dialog translatable might be weird. I think I've cracked how to make it translatable. Stay tuned...
As @TheDJ said in T146393: The CodeEditor interface (options available from toolbar) should be translatable:
I think that the position of Ace on this is that any UI that is available is only a demonstration of what you can do with Ace. Thus if you need translations, you need to build your own translatable UI elements.
@Nardog Is this still blocked on making the interface translatable? I think i18n is a good-to-have but not required for the first pass of this feature. All code pages have the page content language of English.