Sorry I didn't manage to implement your tutorial into my context.
Actually I have never used the func_wall_toggle enity. I need to practice it with maybe another tutorial.
For my sake I used +0BUTTON2 which switches to another texture (+ABUTTON2) when the button is pressed.
BUT that makes a basic On/Off switching. I search how to have a temporary switching.
1) texure off
2) texture on for ~50ms then revert to texture off automatically
I used +0BUTTON2 and a func_button entity with the flag Don't move and a Lip parameter to set the time