Almost perfect

There are, however, a few usability / UX issues for users who aren’t familiar with Polylang and try to use it for the first time.

• The fact that when viewing a list of posts in wp-admin, translations don’t necessarily show up below the original post (or default language’s version of this post). So translations aren’t grouped together in post lists. I agree this is hard to achieve but it would be possible using a single WP_Query
• When editing a post, there’s a field for the post language and its translations in the right side bar. Some users misunderstood this and thought they had to select the other language from the “Language” dropdown to switch between language versions.
• There are situations when users do not specify a post title. For one example, in a certain theme, there were “portfolio” posts containing images and text shown on them. One user just created plenty of portfolio entries without titles – making it impossible to directly translate those. You cannot link posts with empty titles together with Polylang unless by using the API (which I did in this case). This doesn’t even work when using the “+” link next to a post with an empty title. Of course, in most cases, posts should have a title but it shouldn’t be necessary for Polylang to work

Apart from that, Polylang works really well and I’ve used it in multiple projects.