The Ancient Greek:
Nepal is not an easy place to fly, there is simply too much geography and too much weather for the normal rules to be 100% reliable.
Nepal is a very demanding place to fly, precision navigation is essential and the slightest mistake can be fatal.
There are no easy answers.
Some mountainous areas are just plain high risk, especially where there are the weather factors such as those that exist in Nepal.
Related to this is that some "experts" saw RNP AR in high-end birds as a panacea for mountainous terrain airports. Not so; there still has to be a reasonable terrain environment to make it all fit.