If it were amended in 10 or 15 years to affect other positions that had been created by Parliament, it would be really useful to have the preamble set out the purpose of this legislation. Having said that, as a former journalist and as a non-lawyer, I will ask Maître Tremblay to contribute to your understanding of this.
Evidence of meeting #74 for Official Languages in the 41st Parliament, 1st Session. (The original version is on Parliament’s site.) The winning word was amendment.
A video is available from Parliament.