I've analyzed this task. If I was to estimate this I would be an XXL at the current point. This feels a little like a mini-epic.

Currently the language menu (ULS) is displaying results in a single column

This is not true. It's actually a lot more complicated than this. A single column will be applied if either the screen width < 500 or the number of languages is less than 24

The logic for this is as follows:

			if ( screenWidth > 900 && languagesCount >= 48 ) {
				return 'wide'; // 4 columns
			}

			if ( screenWidth > 500 && languagesCount >= 24 ) {
				return 'medium'; // 2 columns
			}

			return 'narrow'; // one column

On top of this languages are currently grouped by language class when more than one column is used. A lot of thought appears to have gone into this and similar groups are grouped together and arranged by region. (see "Screenshots of current experience" below for examples)

Now... Potentially we could change the logic so language count is not considered:

This change however would also change the display for existing Vector usages.

For several reasons, if we want to take this on, we should do so with involvement from the language team reviewing the history of this decision and whether it should be changed.

Given the code here is extremely complicated (even for me who is somewhat familiar with the code) it is my recommendation that our team does not tinkering with the status quo without upfront support, insight, and code review from the language team.

Screenshots of current experience

https://patchdemo.wmflabs.org/wikis/796258b4f19bcff4ce8db662ed396b26/w/index.php/Spain?useskinversion=2 (282 languages)

https://patchdemo.wmflabs.org/wikis/796258b4f19bcff4ce8db662ed396b26/w/index.php/Common_Agricultural_Policy?useskinversion=2 (35 languages)

https://patchdemo.wmflabs.org/wikis/796258b4f19bcff4ce8db662ed396b26/w/index.php/Agricultural_subsidy?useskinversion=2 (15 languages)

@Jdlrobson passing this back to you, please pass it back to me once you've had a chance to create the patch demo

See T275089#6842294

No this is existing behaving and presumably QAed when this was initially built. We haven't changed anything so it doesn't seem useful to QA.