I think the questions can be changed. I know that Statistics Canada will be opposed to this, since the organization can no longer compare the new data with the old data if a question is changed too much. However, there are ways to do this.
Keep in mind that, until 2001, there was only one question on the language spoken at home and it concerned the language spoken most often. There was a great deal of pressure to establish that even if people don't speak French the most often, it doesn't mean they're assimilated. In 2001, Statistics Canada added a new question regarding whether another language was spoken regularly. This helped enumerate about 40% more people who use a language. I think that if we did something similar for the first question, we could keep the question, but change the instruction. It would be the same question, but we could then ask about a second language learned at the same time as the other language and a second language that isn't spoken as often.
I could give other indicators based on the analysis of the census data for children aged four and under. Among exogamous families, there are about 30% more people who use French regularly with children aged four and under than people whose mother tongue is French. Among endogamous families, the number is exactly or almost the same. This indicator shows that respondents are not encouraged to provide information. If children regularly speak French at home and the number is even higher when it comes to knowledge of the language, meaning the ability to hold a conversation in the language, and if the language spoken by children aged four and under is not their mother tongue, then what is it?
There are many issues of this nature.