I've looked into it. Well, for starters - you made your enemies ALWAYS (event #7) have the speed of 80, so even if they collide with something, they will instantly gain the speed of 80. :)
Try using something else, for example:
1. if ENEMY is NOT colliding with obstacle AND ENEMY speed < 80 - set ENEMY speed = 80
2. if ENEMY collides with obstacle AND ENEMY speed >= 80 - set speed to 5 / bounce / something else
The problem is that every each second (or tick) the program makes your monsters have the speed of 80, so collisions don't work.