Thank you for all this @alltagsverstand. I finally got it - had to install gnu-sed and use gsed instead of sed. Then all seems to work exactly as described.
The note sequence was what I thought was so powerful about zkn3.
It really helped me organise notes and thoughts, It seems thats mostly how most of my notes has been connected, in these sequences.
Seems I have to go through note by one and then link them together - you are not aware if there us a way to do this with regex in zkn3?
As someone that has been using Obsidian, what would be the best way to emulate this? Just by making ‘table of content’ style overacting notes?