I recently converted VM 1.19 to 2.6.12.2
I have a problem though where a number of the add-on components including the UPS module and order emails are not pulling the language files. The only way I've been able to solve this is to copy all language files from the components into the Jommla root language folder. /joomaroot/languages.
Unfortuantely this means that every extension I have to find and copy the language files... ...but issues still keep popping up. It makes me worry that something major isn't functioning properly.