Question: Is pronouncing loanwords according to their "native" pronunciation stigmatised across most cultures and languages?

This is a leading question. The assumption is that all cultures frown on pronunciations that are accurate in the language of origin. This cannot be determined and is not even a valid linguistics question.

Also, stigmatize is not the right word here. A much better term, even though it does not change the fact this is a leading question would be: frowned upon.

Generally, people are stigmatized, not their behaviors.

Finally, no question about pronunciation can be answered "across all cultures". A best one could design a survey in and for a particular language but even then it would not provide an answer for, say, all the French speakers in France.

My conclusion is that this is not a valid linguistics question. All that can be provided are opinions and clichés that people might have in their heads about a particular way of pronouncing a loanword in a particular language.

Question: Is pronouncing loanwords according to their "native" pronunciation stigmatised across most cultures and languages?

This is a leading question. The assumption is that all cultures frown on pronunciations that are NOT accurate in the language of origin. This cannot be determined and is not even a valid linguistics question.

Also, stigmatize is not the right word here. A much better term, even though it does not change the fact this is a leading question would be: frowned upon.

Generally, people are stigmatized, not their behaviors.

Finally, no question about pronunciation can be answered "across all cultures". A best one could design a survey in and for a particular language but even then it would not provide an answer for, say, all the French speakers in France.

My conclusion is that this is not a valid linguistics question. All that can be provided are opinions and clichés that people might have in their heads about a particular way of pronouncing a loanword in a particular language.