www.wysiwygwebbuilder.com

Hello!

Faced with such a problem: the location of the elements does not correspond to the hierarchy in the page code.

A simple example ( how it looks visually in web builder 18 )

1) H1 header
2) Text
3) H2 header
4) Text
5) H3 header

And when you look at the page code in the browser, I see it in a different sequence

2) Text
3) H2 header
5) H3 header
4) Text
1) H1 header

As I understand it, this happens because I deleted some elements and created them anew. Thus, the newer the added element in the project, the lower it is in the code.

Knowledgeable people, can you tell me if this problem is solved in Web Builder 18? after all, this has a very bad effect on SEO promotion!

This is not a problem of WYSIWYG Web Builder, but of how you've designed your layout. So, there is nothing to 'fix'.
WYSIWYG Web Builder gives you control over the object order.

You can change the order of the objects on the page via the Arrange tools (move to front, move to back etc) or in the Object Manager.
https://wysiwygwebbuilder.com/object_manager.html

Also note as you spoke about the SEO. It is better to use layout grids which will help to stack the items in correct DOM and nested orders. Most people who might use layers will have SEO issues no further but soon.

And writing the titles there should be only one h1 tag. Then comes h2 heading and other sub-heading. The contents have to be related with the h1 and the h2 headings and should contain keywords of the content in the headers headers although expressive. You can learn about headers and content on a blog I wrote here