The add-on does support internationalization. Right now there are translations for French and German. I'm always looking for contributors to translate into other languages. If anyone wishes to help, visit the support site on github and edit the files in the /src/_locales/en/ directory. (https://github.com/ssborbis/ContextSearch-web-ext/tree/native-app-support/src/_locales/en)

> By the way, if the right-click menu display position can also be customized (for example, you can choose to display the position under copy and paste), it is even better!

There is a setting for positioning the Quick Menu relative to the cursor with customizable pixel offsets. Do you mean moving the "Search for.." menu item higher in the context menu? Unfortunately, that cannot currently be done with the webextensions API