Ain't a bit of redundancy categorize users with, e. g.: User en and User en-N? Wouldn't be better to categorize users under User:CODE-LEVEL and then categorize the categories instead?

No, we want to categorize our users just as requested.

Babel doesn't currently support the add of two categories. For the Babel extension, you have to choose one or the other.

Now, if you want the two categories, you can perhaps use a bot to add the other cat or use a custom template system instead of the Babel extension.

Change 283425 had a related patch set uploaded (by Dereckson):
Babel configuration for uz.wikipedia (part 1/2)

https://gerrit.wikimedia.org/r/283425

Change 283425 merged by jenkins-bot:
Babel configuration for uz.wikipedia (part 1/2)

https://gerrit.wikimedia.org/r/283425

Mentioned in SAL [2016-04-14T15:54:57Z] <dereckson@tin> Synchronized wmf-config/InitialiseSettings.php: Babel configuration for uz.wikipedia (part 1/2) (T131924) (duration: 00m 26s)

Anything left to do here? Unless I am missing something uzwiki has the same config as wikidata, where users using {{#babel:}} are categorized in both language and language-level. See https://www.wikidata.org/wiki/User:MarcoAurelio for an example. As such, I am not sure why it do not happen here.

Currently in the uz-wp Babel is not fully configured: no categorization by language levels.
See https://uz.wikipedia.org/wiki/Foydalanuvchi:Kaganer/babel-test as example

What's missing, then?

In T131924#3430405, @MarcoAurelio wrote:

What's missing, then?

No category "User en-1" and "User ru-N", as example.

Please compare with https://ru.wikipedia.org/wiki/User:Kaganer:

In T131924#3430405, @MarcoAurelio wrote:

What's missing, then?

Proposed configuration should be equal to this default code:

$wgBabelCategoryNames = array(

'0' => 'User %code%-0',
'1' => 'User %code%-1',
'2' => 'User %code%-2',
'3' => 'User %code%-3',
'4' => 'User %code%-4',
'5' => 'User %code%-5',
'N' => 'User %code%-N',
);
$wgBabelMainCategory = 'User %code%';

The extension itself is already setted up, this is more of a site request.

Change 751545 had a related patch set uploaded (by MarcoAurelio; author: MarcoAurelio):

[operations/mediawiki-config@master] uzwiki: Amend Babel configuration

https://gerrit.wikimedia.org/r/751545

Change 751545 merged by jenkins-bot:

[operations/mediawiki-config@master] uzwiki: Amend Babel configuration

https://gerrit.wikimedia.org/r/751545

Mentioned in SAL (#wikimedia-operations) [2022-01-10T12:18:27Z] <taavi@deploy1002> Synchronized wmf-config/InitialiseSettings.php: Config: [[gerrit:751545|uzwiki: Amend Babel configuration (T131924)]] (duration: 00m 59s)

All OK, thanks a lot!