It's very hard to explain too 😄 I'm trying to obtain the layout that you can see in the second screenshot within only one text frame per page using the paragraph styles, but it seems not to exist a column setting that allows the text in the left column to pass in the next page staying in the left column. 🤔
This is a case of really needing the extra text frames, so that the text can flow: blue text flowing from page 1-2 and the same with the magenta. They can't flow side by side with column spans. And a table might look like a possiblity, but cells can't break across pages so that's out, too.