Why there are seams that are only visible from a distance?
Probably because texture bleed margin is too low.
Ty, is there any rule about how width margin should be from uv template and should I change the unused uv map space from transparent color to something else?
It’s not certain that the original problem is because of the UV islands and texture bleed margin. You haven’t provided the .blend file with the texture packed in so there is no way to confirm that.
But looking at the image you sent, it’s possible. Some of the UV islands are on the image edge. If it needs to show pixels outside UV island, it gets transparent pixels if the texture is repeated. If it’s clipped, same result. You could test that by scaling UV islands in a bit so they clearly are inside the colored areas, and off the image border.
All UV islands should be surrounded with some margin and the texture should bleed considerably. If there is room, it’s better to fill with texture border color than leave it transparent or some other color. UV islands could also utilize that texture image better than what they currently do. Areas that need to be more detailed should cover more of the image than less important areas.
I would also suggest to check the tutorial linked in my signature.
Use more time to prepare your questions in the starting post, provide more information and the means to answer your questions quickly and clearly. If you do that, you get fast and clear answers. If you instead show that you don’t bother to spend much time doing so, and would rather see someone else spend their time presenting possible solutions and asking many questions, your experience will be very different. This paragraph is already much longer than any of your posts on the forum so far, which is fine if your attachments speak for you.