We can actually get it from the MW API - https://en.wiktionary.org/w/api.php?action=query&meta=siteinfo&siprop=general%7Cnamespaces%7Cnamespacealiases%7Cstatistics

"case": "case-sensitive",

Based on this PHP config of https://www.mediawiki.org/wiki/Manual:$wgCapitalLinks

		// 'case-insensitive' option is reserved for future
		$data['case'] = $config->get( 'CapitalLinks' ) ? 'first-letter' : 'case-sensitive';

But then it can vary per NS on a wiki

"6": {
    "id": 6,
    "case": "case-sensitive",
    "canonical": "File",
    "*": "File"
},
"7": {
    "id": 7,
    "case": "case-sensitive",
    "subpages": "",
    "canonical": "File talk",
    "*": "File talk"
},
"8": {
    "id": 8,
    "case": "first-letter",
    "subpages": "",
    "canonical": "MediaWiki",
    "namespaceprotection": "editinterface",
    "*": "MediaWiki"
},
"9": {
    "id": 9,
    "case": "first-letter",
    "subpages": "",
    "canonical": "MediaWiki talk",
    "*": "MediaWiki talk"
},

In fact... We already do at https://github.com/reedy/AutoWikiBrowser/blob/master/WikiFunctions/SiteInfo.cs#L189

https://github.com/reedy/AutoWikiBrowser/blob/master/WikiFunctions/Variables.cs#L743-L744 should probably be removed

https://fr.dicoado.org/wiki/api.php?action=query&meta=siteinfo&siprop=general%7Cnamespaces%7Cnamespacealiases%7Cstatistics

"case": "first-letter",

Which means $wgCapitalLinks = true (the default).

Your wiki seems to be misconfigured.

I got it. We don't use $wgCapitalLinks but wgCapitalLinkOverrides. But this is ignored by AWB, as it doesn't use the data par namespace.
So one fix would be for us to use wgCapitalLinks (will try it), and for AWB to adapt accordingly to data per namespace.
Thanks for your time!

In T254661#7202807, @Raphoraph wrote:

So one fix would be for us to use wgCapitalLinks (will try it), and for AWB to adapt accordingly to data per namespace.

Or if you set $wgCapitalLinks = false, AWB will follow it, and then you can use $wgCapitalLinkOverrides to turn this off for the NS you dont' want it to be the case. Basically, invert your current config.

AWB then won't change the capitalisation for anything on the wiki.