Dunno if this was posted beyore .
This is what u need : wow client wit Engb/enus and other languague pack , also engb and enus works
in Data\languaguepacku using always write the realmlist of your realmlist , or the realmlist of the server you play on,
in the other Data\enUS(enGB)(enES) that you dont use , put
retail realmlist (set realmlist eu.logon.worldofwarcraft.com)
save everything and exit ,
What do you achieve doing this ? :
Everytime you open your wow , if you put your info of the retail account , it will connect to oficial servers , if you put info of the private server you play on/you own it will log on in the private server automatically