I used 2 of my "Capture a Pearl horse" and did not receive pearl horses. I used one of them in the meadow to help boost my chances.

The tokens guarantee a horse of the colour/gene they are. That means that a Pearl horse token guarantees that the horse will very pearl, so using it in the Meadow just makes it more expensive. No, the token does not guarantee that the pearl will be visible, just that the horse will carry it.

Ah ok. Looks like I will be using those sparingly then. Thank you. Was super excited to use them on this event but not going to now!