Business Line Extend has Theme Options where you can change the Theme Generated Texts into your own languages. The best way of multilingual website is creating different sites with sub-domain like en.domain.com, fr.domain.com or with sub folders like domain.com/en, domain.com/fr. You should install WordPress and the Theme to all of those. You can then link those sites with each other from Appearance > Menus or Putting your code of switcher in header.php. All standard sites use this technique like wordpress.org, microsoft.com, google.com etc. Automated Translators can’t do all you may want
Unfortunately we can tell nothing about any third party plugins.
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