Firstly, let me say I have no issue at all with Dave's pronunciations.
It is a fact that words cross language boundaries and that is a big part of language development. It is inevitable that there will be some local affectations which will change certain elements of pronunciation - for a number of reasons. One is that there are often sounds that are not a natural part of the local language - such as the "ll" which you can find at the start of many Welsh words. The result is that you will get a local's approximation. This may annoy a natural speaker of the other language - but it is not a whole lot different to what makes up various accents.
One of the other really big factors (IMHO) is that, in the case of Kirchhoff for example, we see the name presented as text on a page. There IS no guide or reference in how it should be said - so it is simply vocalised using the rules of pronunciation that we grew up with. Once this pronunciation finds life, it is pretty well there forever. So don't blame the early speakers for their efforts - they didn't have someone to tell enough people how to say it properly in the first place.
Also, not everyone who comes to a new country is precious about pronunciation. About 60 years ago an immigrant started up a business in my town - and he was more than aware of the challenges of language. He made no issue of the pronunciation of his surname and he adopted the first name of 'Albert' because - and he said this himself - that people would have a problem with his real name. His real name was Umberto. Today, this isn't a problem at all for the majority of Australians, but back then it would have been almost like someone speaking in Klingon.
My how times have changed - but he still goes by the name 'Albert'.
For those who champion 'saying it right', there is a positive trend, however. As Australia - and, indeed the world - is finding itself exposed to ever increasing multicultural diversity, we are becoming more aware of the differences in language, new sounds are becoming more familiar and we are broadening our appreciation of other cultures and language.
Go back a few years and usage of an alternative (ostensibly the 'correct') pronunciation would have just caused little more than confusion. These days, the confusion is a little less - but there is a time cost as the alternative pronunciation is translated into the one the listener understands - much like when you learn a new language, you have to translate the words into English in order for you to understand the message.
However, for those words that gained the Aussie (or any other country's) pronunciation/accent from all those years ago, the news is simple: Common usage has now cemented their sound into the local vocabulary....
... for the time being.
These things may well change - as language is always evolving - but for now, I suggest not turning it into a witch hunt.