Wow, the battle menu looks great.
You can check how much width a drawn string will take by using this command:self.contents.text_size(YOUR_STRING).width
This method will return to needed width for the string called YOUR_STRING. BTW, you should always add 4 or 8 pixels, since sometimes it's not 100% accurate. Also note that italic letters are not being considered.Find the def draw_item(i) method in Window_Selectable, copy it into the code of your window and mess around with this command:
self.contents.draw_text(4, 32*i, 128, 32, @commands[i])
or very similar to this one. You need to work with the 32*i, try changing it to 36*i and look if it fits. Also, don't forget to change the height of the window and the height of the Bitmap. Best is you don't use the default Window_Command, but make another class with the Window_Command as superclass like:
Window_BattleCommand < Window_Command
Or just read the e-mail and after you've sent me the files, I'll do it for you.