It seems like column is the only grouping for multiple cards currently, it will be so much easier and more flexible to have grouping for mindmap, like the miro and obsidian canvas.
Column is great but arrow can’t be placed to the cards in the column, but having group feature I believe you can add arrow, which I think is very important, coz board view is the main thing in Scrintal and improving the visual features like the use of arrow, or even allow different style like dashed / dotted arrow or various colour will help a lot in mind maping.