Presumably the Scottish, Irish and Welsh imperialists, together with the English, - ie the British imperialists - were the ones who prevented the Maori and Aborigianal languages from being used, many of which are now lost as a result.
Many Aboriginal languages are lost because up until the 1970s government policies banned and discouraged Aboriginal people from speaking their languages. Members of the Stolen Generations were one such group.
In many cases, children were barred from speaking their mother tongue at school or in Christian missions.
“Sometimes Aboriginal parents also thought that their language would hold their kids back, so they wouldn’t use it,” Professor Michael Walsh, an expert on Aboriginal languages, says [1].
Early attempts to document Aboriginal languages usually focused on simple word lists for novel items such as weapons and animals.
First Fleet officer William Dawes is a notable exception. He recorded conversational snippets of the Dharug language spoken around Sydney that tell of the social and cultural contexts, personalities, actions and feelings of the Aboriginal people he interacted with [2]. Dawes was taught by a 15-year-old Aboriginal girl named Patyegarang
I have read a book about Dawes - an Englishman from Hampshire.
Not everything is black and white, it was British not English imperialism. And the British were not the only imperialists.