The sentences are correct as they are. This attributive use of the participle is very common.
Simply said, you can use a participle in much the same way as an adjective (it is not completely the same, but I won't go into the details now.)
You can use adjectives to describe a noun:
I own a blue car.
Instead, I can use a present participle:
I'm in a moving car.
Or I can use a past participle:
I'm looking at a painted car.
This is exactly how those two particples are used in your sentences.
They talk about stories created (by someone) and art works carved by someone.
As for your alternative version, you can rewrite the sentences but not as you did it. You need to add more:
The public will be able to listen to the stories that were created by the teenagers and look at the symbolic art works inside these wooden dolls, that were beautifully carved by the Dublin Woodturners’ Association.
Instead of were you can use are, the difference between those is a completely different topic.
Do note that art works is plural so your suggestion of singular was would bot work!