This form is completed for all persons included in the application that are Pakistani nationals and above 18 years old.
NO
Some forms are generic and are used for other immigration streams where couples are immigrating together. That's why [N/A] boxes are placed there. If both Sponsor and Principal Applicant's information are required in forms, they would place that form under "BOTH SPONSOR & PRINCIPAL APPLICANT".
In Document Checklist IMM 5533, IMM 5562 and IMM 5536 are ONLY included under PA's forms list, not Both. Therefore, it must ONLY be filled by PA and only PA's information is required.
For Spousal Sponsorship purpose, Spouse is primarily considered as "SPONSOR".
Principal Applicant's forms must ONLY include those who are also accompanying him/her as Dependent (not as sponsor). For application purposes, your Canadian citizen/PR spouse is not your "spouse", they are only the sponsor and they do not fill out any PA forms. These forms are generic for all streams of immigration, so they are not referring to Canadian spousal sponsors, they are referring to spouses of applicants applying through another stream (parent, skilled worker, EE, etc). IRCC already have travel history of Citizens / PR.
If you still have desire/urge to fill your Canadian Sponsor's details on PA's supplementary forms, there's no harm in doing that. However, No file was refused/returned in both cases.
NOTE : [IMM 5562]