Yes you're right - the form is for the PA to fill out but since they have a section for the spouse's travel history, I think it needs to be filled out - at least that's what we did in our application when we submitted in June 2017. The way I viewed it is that NDVO will probably check to see that travel dates match if you and your spouse traveled to visit each other.But form imm5662 is for principal applicant...so I am in dielema.
That's just my opinion but maybe somebody else in the forum can confirm if this section of the form needs to be completed by the sponsor?