Phoebe's Text Box Conflict

If a Phoebe, Head of S.N.E.A.K. steals multiple text boxes that contain abilities that set power and toughness (ex. "This creature's power and toughness are each equal to the number of swamps you control."), is her power and toughness determined by the newest stolen text box or as a total of all those abilities' counts?

From the Unstable FAQ:
What happens if two text boxes contradict one another? For example, say it picks up two text boxes that each set its power and toughness differently.
The most recently added text box wins if there is a contradiction. Let’s say Phoebe steals the text boxes of both Beast of Burden (power and toughness equal to the number of creatures on the battlefield) and Psychosis Crawler (power and toughness equal to the number of cards in your hand). Phoebe’s power and toughness would be defined by her more recent heist.

Beast Beast of Burden Creatures Phoebe, Head of S.N.E.A.K. Psychosis Crawler The FAQ Unstable Your Hand