I agree that such a target makes sense for close distances and for judging the accuracy better. Not only because of the circular shape, but also because the balls are caught in the corresponding net. Nice craftsmanship.
But in competition I wouldn´t care what the shape of the target is, as long as everybody uses the same one.
I watched the video but sadly I can not understand your language, so I have two questions:

What are the rings made out of? Plastic tube?

And what is the dimension of your backstop net? I feel that I need one of that size to mount between trees.

This is a very cool concept! Well done on the execution - it looks so well made!

Interesting idea!
It seems like in practice there's a slight problem with the balls bouncing on some shots; perhaps the net should be moved deeper in certain areas.
Also, in my opinion, the most prominent ring here is the yellow one, and it's the outer one. It should be the other way around, with the center ring being the most striking and expressive.

We conducted this tournament according to the sparring system. All the participants really liked this format. The principle of the tournament is simple. Sparring with everyone. Two people come out and sparring takes place between them. Winning a set earns 2 points. A draw is 1 point. Defeat is 0. As a result, whoever gets 3 points faster in the total of the sets wins the sparring match.  As a result, the sparring can consist of two or more sets until the winner is determined. If the number of points is equal. For example, 3x3 or 4x4, then the participants throw one ball each. Whoever got there first won the sparring match.

https://rutube.ru/video/95d4475d0f2e88c0ea8dd411b7ea7a1e/

The idea to create a full-fledged target with three zones appeared a few years ago. There was a lot of trial and error, and finally the puzzle came together. It took about six months for various tests and selection of materials. And as a result, a new full-fledged large 3-zone Goliath target was born. The name came by itself-the central part of the gong is 25 cm-probably about the same size as the forehead of a fabulous Goliath. The base of the target, like that of the Balearics, is a 120x120 cm shield with a 50 cm circle in the center.(Diana). And there were changes in the design of our target, which radically changed the course of the competition and the rules for calculating the results. The square is 120x120, followed by a circle-Diana, measuring 76x76 cm. In the center of Diana is a window in which a movable metal gong hangs. As a result, with the increase in Diana's size and the appearance of a third small Goliath zone, it became more interesting to throw, and the fight became even more exciting. Each slingshot is focused on the result and tries to hit the fabulous "Goliath". There were doubts in the slingshot community that a slingshot could hit such a small target and adding a third zone was pointless. But our David and Goliath 2026 tournament proved otherwise. More than half of the participants were able to hit a central target measuring only 25 cm from different distances. Random viewers also liked the target and the tournament, who actively started rooting for the participants of the tournament and loudly welcomed the hits to the "forehead of Goliath", supporting the athletes.