Steps to reproduce the issue

1) Joomla with several languages installed, some using latin characters, some featuring diacritics, some with non-latin characters such as Chinese, Burmese and Thai
2) Aliases set to Unicode and not Transliteration
3) Associations between menu items are all set correctly

Expected result

(this is what appears in the head for English and other languages using latin characters with no diacritics)

base href="http://wilddogdesigngroup.com/us/about"
[...]
link href="http://wilddogdesigngroup.com/us/about" rel="canonical"
link href="http://wilddogdesigngroup.com/mm/မိတ်ဆက်" rel="alternate" hreflang="my-MM"
link href="http://wilddogdesigngroup.com/cn/为什么选择我们" rel="alternate" hreflang="zh-CN"
link href="http://wilddogdesigngroup.com/id/mengapa-kami" rel="alternate" hreflang="id-ID"
link href="http://wilddogdesigngroup.com/my/kenapa-kami" rel="alternate" hreflang="ms-MY"
link href="http://wilddogdesigngroup.com/th/เหตุผลที่ควรเลือกเรา" rel="alternate" hreflang="th-TH"
link href="http://wilddogdesigngroup.com/vi/tại-sao-chọn-chúng-tôi" rel="alternate" hreflang="vi-VN"

Actual result

(this is what appears in the head for languages using non-latin characters (Chinese, Burmese, Thai) as well as latin characters with diacritics (Vietnamese); the example below is from Thai)

base href="http://wilddogdesigngroup.com/th/%E0%B9%80%E0%B8%AB%E0%B8%95%E0%B8%B8%E0%B8%9C%E0%B8%A5%E0%B8%97%E0%B8%B5%E0%B9%88%E0%B8%84%E0%B8%A7%E0%B8%A3%E0%B9%80%E0%B8%A5%E0%B8%B7%E0%B8%AD%E0%B8%81%E0%B9%80%E0%B8%A3%E0%B8%B2"
[...]
link href="http://wilddogdesigngroup.com/th/เหตุผลที่ควรเลือกเรา" rel="canonical"

System information (as much as possible)

PHP Built On Linux serv01.ams2.siteground.eu 2.6.32.59-sg3 #9 SMP Wed Sep 26 03:29:25 CDT 2012 x86_64
Database Version 5.5.32-31.0-log
Database Collation utf8_general_ci
PHP Version 5.3.29
Web Server Apache
WebServer to PHP Interface cgi-fcgi
Joomla! Version Joomla! 3.3.6 Stable [ Ember ] 01-October-2014 02:00 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT

Additional comments

In a nutshell, the alternate URLs are correctly appearing in the head of the site on pages in languages using latin characters. They don't appear on pages with latin characters + diacritics (Vietnamese) or non-latin scripts (Chinese, Burmese)