Your concern about user confusion is founded . I got confused by only reading your question. I do not want to immagine the confusion for the administrator of this site. :-)
I would re-think the basics , or the blueprint of the install .
You could very easily achieve the same result in a more user-friendly , and Admin-friendly way by using the excellent qtranslate plugin.
This will allow you to have domains like :
- de.example.com
- en.example.com
- ro.example.com
or, if you want :
- www.example.com/de
- www.example.com/en
- www.example.com/ro
It will also allow you easily have different content , titles, and , with an excellent hooks and filters system - and a bit of custom coding - even different URLS and language based SEO. All in the same install.
Even the little flags that you wanted comes out of the box .
Qtranslate also has quite an active community and forum for hacks.
If you will use it , You can then do something like
$ccTLD = end(explode('.', $_SERVER['HTTP_HOST']));
if ($ccTLD == 'com')
define('WPLANG', 'en_US');
else
define('WPLANG', 'ru_RU'); //or other language
( See more details here - BTW - IMHO the hack is not needed , filters can be used )
But like I said before , you will not really need it if you plan the installation correctly.
You also have choice to use the domain mapping plugin to map the domains correctly to the corresponding section ( or better yet - do that manually in cPanel / Plask )
IMHO - multiple installs is a sad choice for such a site ( unless it will also use different plugins, different theme, different everything...)
Give qtranslate a chance - I am almost sure that after you will learn and try it - you will rethink the framework for your installation.