Just FYI, once you have changed the language in WordPress settings then you need to translate the strings of this plugin to Spanish then only it will reflect.
and please take my suggestions into account, I really like your plugin is what I have looked for but with these suggestions it will be even better and congratulations for your plugin very good work
The only thing I can assume is that maybe we have different file locations. I have set it to this https://prnt.sc/qnnmsd so if you do not have the same location please relocate the file and test.
Once again thanks for your suggestions, I will see what I can do in future releases.