Congratulations on the release of content HUB, this is a huge mile stone!! You have done us proud again H5P!! Is there
This is an interesting version of column/interactive book... the idea is to be able to add more than one type of content horizontally as well as vertically. I feel if it is implemented in column then it will automatically be in interactive book. Sample below!! this will definitely improve the vertical only layout of columns. A cool thought!!
A possible work around is add a small new content type that allows adding two to three different content types horizontally and that to be added to column!!