Try deleting the file clientregistry.blob in the Steam directory. You'll have to sign out of Steam first before you can do this.
After that start Steam up again, you'll have to enter your login details again.
Then try verifying the game cache for Blade Symphony.
You can do this by following these steps:
Right-click on "Blade Symphony" in your list of installed games and select "Properties" from the menu.
Then you need to select the "Local Files tab" and click the "Verify integrity of game cache" button.
Steam will verify the game's files - this process may take several minutes.
Once the process is completed, the Check Window will automatically exit.
If there are any corrupt/missing files, then they should have been downloaded in this process.
I followed your instructions, but it didn't help. At "Verify integrity of game cache" step Steam has found 5 broken files and redownloaded them, but after that the game switched to Russian completely (despite being set to English in Steam) and that's it.
After unsuccessful attempt to find some registry key or .ini/.cfg file with the option to change in-game language I came up with clumsy but working solution.
I went to "[...]Steam\steamapps\common\Blade Symphony\berimbau\resource" folder, removed "basemodui_russian.txt", "berimbau_russian.txt" and "gameui_russian.txt", then copied "basemodui_english.txt", "berimbau_english.txt" and "gameui_english.txt" and renamed them to "basemodui_russian.txt", "berimbau_russian.txt" and "gameui_russian.txt" respectively.
This way I have everything in English in game, phew...
BTW, Russian translation leaves much to be desired, there are many errors of all kinds in it...