Unfortunately, we probably need to include translation files within the plugin itself.
The string is translation-ready, but I haven’t generated translation files for the plugin yet. I will work on setting up the translation process in the next few days, so that the plugin will be properly internationalized and l10n-ready. I apologize for not handling that earlier.
In the mean-time, you can attempt to hook into the post-content-shortcodes-read-more filter and modify the HTML that’s output for the Read More link. Thanks.
It looks like you should be able to start working on a proper translation for the plugin if you’d like. You should be able to go to https://translate.wordpress.org/projects/wp-plugins/post-content-shortcodes and choose your language to begin adding translation information there.
Theoretically, with the plugin now being translation-ready, you can also use language/translation utilities within your own site (for instance, if you’re running a multi-language plugin such as WPML) to translate individual strings locally on your site, as well. Thank you.
