I use the Canadian English spell check dictionary (Firefox add on) Why don't you use the Australian one?
As for languages (& versions thereof) evolving & changing, I think you will find that technical terms (remember what started all of this?) do not change meanings as easily as the rest of the language. Most people in technical fields (engineering, medicine &c) understand that it is easier to understand people from other places if all people who speak the same basic language use the same words for the same things.
Besides, with the internet making international communication not only easy but commonplace I expect that many of the regional differences will fade away in a generation or two.