Description
Imagine this. You have a multi-language PW site and you want to add the new language "ProcessWireish"
You go to Setup > Languages > New and add a title ProcessWireish
plus a name pw
:

After save you see this:

Then you want to view the frontpage in your new language and you head over to this url:
- example.com/pw
---> 404
So you might wonder why things are not working. You set the page name to pw
right? So it should show up under /pw
right? No! Turns out a language name and a language url segment are two different things and you forgot to setup the language url segment on the home page's settings tab. That's hidden quite well in the process, right?
My suggestion is this:

This is the code for the warning:
<div class="uk-alert uk-alert-warning uk-margin-remove">Warning: No Url-Segment setup for this language yet. <a href="">Edit the homepage</a> and setup the url segment of this language on the settings tab!</div>
PS: I'm not complaining about the language name being different from the url segment - that's perfectly fine (and necessary, I get that). It's just about helping the user stay in the flow and avoid wondering why things are not working.