The phrase "alter the language of" is correct and usable in written English.
You can use it when discussing changes or modifications to the wording or phrasing of a text or speech.
Example: "The editor decided to alter the language of the manuscript to make it more accessible to a wider audience."
Alternatives: "modify the wording of" or "change the phrasing of".
The two men tried desperately to alter the language of the briefing paper.
The motion to alter the language of §205.203(c) to permit exemption of anaerobic digestate from pre-harvest application intervals did not pass.
Writer James Shapiro was not happy with the Oregon Shakespeare Festival's decision to hire playwrights to alter the language of the plays, making, "O Romeo, Romeo!
But without altering the language of the measure, Representative J. C. Watts Jr., the Oklahoma Republican who was a cosponsor of the initiative, was able to win back most of the wayward Republicans by promising that he would "address their concerns" when the measure was taken up in conference after being passed in the Senate.
People familiar with the decision to publish said that White House officials sought to avoid the political blowback that hit the George W. Bush administration when it was revealed in 2005 that a White House official and former oil lobbyist, Philip A. Cooney, altered the language of government climate science reports to weaken the link between fossil fuel pollution and the warming of the planet.
Today we have altered the language, of course.
Responding to the shift, the Recording Academy last year altered the language of its soundtrack awards to more specifically make it clear that video games were in contention.
A number of rules were developed in the adaptation of the PREVENT manual, to systematically alter the language and tone of the US version.
And enough to alter the language we use, as evidenced by dictionary updates centered on heads of state past and present.
