I agree with most of what you say. As for the salaries though, you cannot pay an employee less than what an Australian makes. That is against their labor laws. Furthermore, the cost of living is very high, as are income taxes. However, most of those so-called 'employees" are relatives of politicians "vacationing" abroad at the expense of Sri Lankan taxpayers. Yes, they should be asked to return forthwith.
Diplomatic personnel should necessarily be highly qualified and experienced. Above all, they should be ardent in discharging their duty to the fullest satisfaction of the country and people. Their ambit or scope of work is wider than they think or claim. What if the government sets targets for our diplomats from time to time and subject them to constant supervision?