Wikimedia Bugzilla is closed!

The correct regex would appear to be:

/^([a-zА-Яа-яӘәҒғҚқҢңӨөҺһҮүҰұІі]+)(.*)$/sD

That *should* whitelist all the Kazakh-Cyrillic characters for linktrail, if I
have them correct (from [[Kazakh language]] on enwiki).  It would be possible to
institute this change locally by just getting an admin to change
[[kk:MediaWiki:Linktrail]].  (Any additional characters you might want go inside
the square brackets with the others; you can use ranges in Unicode order like
[a-i] or just a list of characters like [abcdefghi].)

(In reply to comment #1)
> The correct regex would appear to be:/^([a-zА-Яа-яӘәҒғҚқҢңӨөҺһҮүҰұІі]+)(.*)$/sD
Not at all. It isn't work.
Last change is 

[[kk:MediaWiki:Linkprefix]]:
/^(.*?)([a-zA-Zа-яА-ЯäçéğıïñöşüÄÇÉĞİÏÑÖŞÜʺʹёәіңғүұқөһЁӘІҢҒҮҰӨҺ«„]+)$/sD

[[kk:MediaWiki:Linktrail]]: 
/^([a-zа-яäçéğıïñöşüʺʹёәіңғүұқөһ“»]+)(.*)$/sD

It appears correct? But still don't work...

I've been informed that MediaWiki:Linktrail no longer functions.  This will have
to be entered into a new language file.

Fixed in r15938.