Canonical chains may confuse and mislead search engines like google and yahoo. Subsequently, they may misinterpret or dismiss the required canonical. The JS redirect seems like a bit of a messy condition, but to answer your dilemma: When you set a canonical tag from ourdomain.be to ourdomain.be/en, then I wouldn't https://seolistlinks.com/story20124465/considerations-to-know-about-prestashop-canonical-url