How to change the Language of ROSE
Currently there are two languages supported by the client itself now.
To change from one to another while in game press Alt+O and click the interface tab, the first drop list is the Language options.
Possible Client Corruption Fix
When you have a corrupted client/installer its frustrating I know its happened to me plenty of times!
I found that copying the ROSE Online folder and having at least one back up from a "good" or successfully patched client is a good idea. When you have a "good" folder copy it and put it somewhere safe, mine are in 1. C:\Program Files\Gravity\Rose Online and 2. C:\Users\username\Documents\Rose online. This second one is only for backup NEVER patch with the one in that folder to preserve it. If the first one does get corrupt just open the second folder and push (Ctrl+A) to select all inside the folder then right click and copy, then go to the first folder and hit (Ctrl+A) and right click and paste (it may ask if you wish to overwrite the files click yes).