[TomTom]

Now as for recursively triggering changes the following modifications to the script file work well;

game_manager
{

    ////////////////////////////////////////////////
    // Initialising

    // When game starts
    spawn
    {

        // Level initialization

        . . .

        wait 1500

        // TomTom random the house
        wait 5000
         trigger game_manager random_setup //6 lines moved into a trigger scriptblock called by this line
    }
    trigger random_setup
    {
        // original 6 lines moved from game_manager spawn
        wm_announce "random setup now!"
        accum 0 random 255
        trigger game_manager random_floors
        trigger game_manager random_walls
        trigger game_manager random_crates
        trigger game_manager random_grates

        //new lines here on...
        wait 15000                //minimum 10+ second delay, increase to taste

        //console cvar to manually stop the recursion, (can still manually change)
        cvar Fritzbot_stop_random abort_if_equal 1

        //warn the player
        playsound sound/world/alarm_01.wav volume 255
        wait 1000
        playsound sound/world/alarm_01.wav volume 2000
        wait 4000
        //recursive call to loop the script block
        trigger game_manager random_setup    //note: infinite recursion is normally dangerous to the stack 
    }
. . .

The script block random_setup will now handle the calls to change the 4 types of barriers. It also checks to see if a new console cvar is set to 1. This is to allow the server sysop to stop the infinite random changes in the playfield. If hosting the game open the console (`) and type /set Fritzbot_stop_random 1 to kill the random barrier changes (manual lever changes still work). Once turned off you have to restart the map to restart random barrier changes.

You can make the changes to a copy of et_headshot.script copied out of the waypoints into fritzbot\maps. You will have to then play using /sv_pure 0 to use the modified scriptfile versus /sv_pure 1 to play with the original waypoints.
BTW If you want to support more than 2 possible script files for the same map that can be done by setting a special built in ET cvar.