I think it's a good idea to add the target to the bill. However, my colleagues and I really view Bill C-12 as a governance framework. Consequently, we feel it's somewhat less important that the bill include the exact figure.
However, we want to have assurances that the government is accountable within the framework of all the mechanisms and processes. To ensure that's the case, it must be clearly stated who is responsible for meeting the target and how it will be met. The language must also be clear, as you mentioned.
I'm not a lawyer. I did a minor in law and that was enough for me. However, what my lawyer colleagues and experts in the field tell us is that language is very important. So we should prefer words like "shall" and "meet" over others such as "try" and "permit."