WordPress has had support since version 4.7 for admin users to choose the language that they wish to use the admin area in, separate from the language used to display the front-end of the site.
It’s possible for you to run a site where the administration users interact in English, but the front-end of the site is displayed in a different language, e.g. French. This kind of setup doesn’t require the use of a multi-lingual plugin since front-end content only exists in one language.
By default, Say What? Pro only enables per-language string replacements if it detects a compatible multilingual plugin active on the site. However, if you’re running a dual-language setup using the built in WordPress user language selection, you can enable the features by adding a small plugin to your site:
* Plugin Name: Language-specific replacements for Say What? Pro
* Plugin URI: https://plugins.leewillis.co.uk/
* Description: Enables language-specific replacements in the Say What? Pro plugin
* Version: 1.0
* Author: Ademti Software Ltd
* Author URI: https://www.ademti-software.co.uk/
add_filter( 'say_what_multilingual_enabled', '__return_true' );
Once this is installed, and active, you’ll be able to set replacements per-language as if you were running a multi-lingual frontend.