I guess I will continue complaining about this, as I did here (https://phabricator.wikimedia.org/T136677 – not sure if it was the right place) and repeat my comments.
This feature is annoyingly complicated. Please make the list more simple, and get rid of the pop-up window. A similar approach that has been taken for the mobile version would be good. I don't understand the need for this kind of complexity. For example, compare a situation of a typical article with 17 interwiki links in the English wiki and the Finnish one: which list is more complicated to navigate, the English one with 17 languages – or the Finnish one with a separate scrollable pop-up window, five different categories and two columns of text!?
Hiding the interwiki links like this actually causes me a lot of extra trouble instead of helping me. I am interested in a fairly wide array of languages, as well as seeing, which languages are available for a given topic. For example, on the Finnish Wikipedia page on Philippe Buonarroti (https://fi.wikipedia.org/wiki/Philippe_Buonarroti), nine interwiki links are shown and seven are hidden. I have to open a pop-up window to know which languages they are. Instead of showing me a list of those previously hidden languages, I have a long list of all the available languages grouped into eight (!) different categories, some geographical and some not, with some languages repeated (e.g. Russian is on the list three times, and English a full eight!). If I was searching for Hungarian, for instance, I would have no way of knowing whether it actually exists, and I would have to browse through a long and confusingly, unintuitively arranged list to actually know that yes, there is a Hungarian article available on the topic (if I ever made it that far). This feels outright discriminatory in some ways.
It seems to be a larger trend to only show users content that a service presumes that they would be interested in. I'm sure that this is often terribly useful, although sometimes problematic (as in the case of Google algorithms that leave out certain search results and bring up others, for example). Here, however, that is currently executed in a way that I find quite annoying. Using a simple, alphabetised list in which what you see is all there is can in many situations actually be easier, more equal, neutral and helpful. Browsing different languages and moving between them, which I like to do a lot, becomes much more difficult with this kind of an arrangement. Now, this does not preclude lifting up some languages to the top of the list, for example (like has been done with the mobile version), but the current version is IMHO a complete mess.