I think what it’s trying to tell you is these tournaments are +EV because the site adds money to the prize pool. Even though they take part of the buy-in, there is a chance that what they add may make the prize pool exceed the amount that the players buy in for. That’s my understanding on this.
I’m not sure if that makes these +EV since the rake on these smaller tournaments tend to be a higher percentage than it is for larger tournaments.
Obviously, if you’re not cashing consistently, nothing is going to be +EV. I would work first on cashing more consistently in these before I worry about what is + or -EV.
I would guess players are pretty splashy/spewy in these Spin and Go’s. Look for some strategy to beat those.