Yep, small surf sails have a reputation for being "twitchy".

Some surf sails are built so that they turn off positively, so that they're easy to depower when needed in the surf.
Trouble is, this kills their bottom end, they need a certain amount of wind to form their full draft. This would make them hard to use for a beginner wanting to start off in light winds.
From what I've seen, North and Ezzy make wave sails that turn on fairly early.
You can tell, by pressing on the rigged sail around the harness rope area, and seeing how much force is needed to fully deflect it.

Cambered sails are more stable but they don't turn off and are harder to rotate, so are not normally recommended for learners.