I do not want to talk in a bad way about this particular mechanic even though he seems to have difficulties in adjusting valves! But in general it seems that everyone who can wear a KTM t-shirt is allowed to wrench on these bikes officially....I could write a book about the last weeks. It is horrible, not to imagine, a nightmare!
What happens if you do forget this screw and let the engine run for a while, using throttle? Could that be the reason why I could see an air/gas-stream spraying out of the carb?