Yes, you will eventually attract more birds as they learn about your food providing plants. And yes, any bird that would normally eat blackberries will help themselves to yours as well as the Beautyberries. It's like sending a kid to the dessert table that has cake and cookies and expecting them to not touch the cookies. Not gonna happen. :)

And there are no stupid questions!

I have beautyberries all over my property and have never seen anything eat them. I just end up with purple stains on my clothes when I mow.

I have 1000's of beauty bushes and the birds don't eat them much at all. Most of the berries end up drying up and falling off. I cut the branches off and throw them to my ducks and chickens and they do like them.

Cardinals seem to eat the beauty berries and another bird I believe might be a cat bird ? The cardinals stay around and will clean out my blueberries. But they don't seem to pay much attn. to the blackberries. I have read that Beauty berries are food of last resort to many birds. They will only eat them when there is nothing else around. They are an important food source in the winter time.

Birds never had a chance to get my berries, the squirrels chewed off all the twigs with berries and carried them off.