Open your Mount&Blade Warband\Modules\Native\strings.txt and find these lines:
str_auto_team_balance_in_20_seconds Auto-balance_will_be_done_in_20_seconds.
str_auto_team_balance_next_round Auto-balance_will_be_done_next_round.
str_auto_team_balance_done Teams_have_been_auto-balanced.
Replace with:
str_auto_team_balance_in_20_seconds
str_auto_team_balance_next_round
str_auto_team_balance_done
Should work maybe. Depends if it will hate on the blank spaces, you could try putting in underscores or .s or whatever if it doesn't work the first time around.