In this case contact plugin author and ask if they support WordPress translation files. Because this string is hardcoded and appears after the Ajax request. We allow translating the mentioned string using theme and core plugin translation files.
So, you may try to create translations for all languages you have as described here https://xstore.helpscoutdocs.com/category/18-theme-translation , translate the mentioned string and check if it works for you. You’ll be able to remove the Loco translate plugin after that, it won’t affect your translation.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.