I do not have cherry shrimp yet. However, I have asked and researched extensively this question - I'm also going to introduce cherry shrimp into an established tank.
Harlequin Rasboras are very unlikely to go after the shrimp. Even if you notice how they eat, they don't forage on the bottom of the tank...they usually eat anything thats free floating or falling down.
With enough cover and mostly mature shrimp, I think your shrimp population will be just fine. If they do breed, you may lose a few shrimplets but I'm sure you can maintain a breeding population in your tank.
I'm introducing cherry's with much more notable shrimp-eating fish and I've been told its possible (though far from guaranteed).
I think you're ok :P