In order to not get penalized by search engines for repeated content, it is important to set correctly the canonical URL tag. Apart from the canonical tag, and specifically for the multi-language scenarios, there's another tag that it is important to use and that is the hreflang tag.
Liferay DXP uses both and in cases where the languages are used just for navigation, so the content is not translated, the current behavior is perfect. However, when the sites are translated into multiple languages, Liferay DXP is not helping to index properly the different versions.
The goal of this epic is to make Liferay DXP manage the canonical URLs correctly for multi-language scenarios, both where all the site is translated, but also when just some parts are translated