I always read through this story wondering how the queen sees everything Canaria does, since she doesn't seem to prove very helpful to her schemes most of the time.
This chapter, however, I can see the facade perfectly. Canaria sews the cloak herself so that the prince gets a shabby cloak that'll hurt his dignity, and he won't be able to refuse a gift from his dear wife. Canaria "feigns" sickness so that Caesar has to either ditch the celebration or ignore his dear wife.
On paper, both are dragging the first prince down with good ol' emotional blackmail. In practice, our pure protagonist boy is too dere to care.