I have fixed this bug, it’s not perfect but it works, you set 3 as an allowed html tag in the kses.php file then in the functions-formatting.php you set it to automatically replace “<3>” with “<3” so the user types “<3” which is detected as an incomplete but allowed html tag so it is completed automatically with <3> and then the formatting replaces it with “<
3″ (you have to use the html code for the < character)