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It is the right way to do it According to this, looks like you should include the <loc>url as well, so add:</loc>

Not at all, if the URL language matches the content of the page then it should be even better that using a full English URL. However, I would suggest using domain.com/ar/blog/عنوان بلوق عربية طويلة حقا على شيء مثير جدا للاهتمام for the arabic blog and if there's an english or french version of that page, you can also implement hrelang on them and point them to domain.com/blog/English-blog-title-really-long-on-something-very-interesting Hope that helps!