what and how these flowers/decorations are made?

The topper looks like isomalt. The side roses are either gumpaste or bean paste. They are usually made one petal at a time. It’s too complicated to explain. Try googling gumpaste rose tutorial.

I thought it looked more like wafer paper…

Flowers look real, but the clear and gold sails are most likely Rice Paper (Spring Roll wrappers). I have a free tutorial on how to make those https://youtu.be/azBMei8aj50

I agree with Anna, Rice paper. I bought the round type made in Vietnam. You soak them in water just until they become pliable, lay them on a piece of parchment paper or a silicone mat, shape them with your fingers and allow to dry. They dry very hard and can be painted with edible luster dust or petal dust mixed with alcohol. I found the rice paper circles on Amazon, very inexpensive. Here are some I made.

I agree that the flowers are real and the sail on top is rice paper. As The Garden Baker said, if you want to learn to make gum paste flowers, there are a million tutorials on YouTube. For example, if you want to learn to make a rose, Google “gum paste rose tutorial” and you will find many choices, all of them valuable.