I would like to request a config to be added to the Columns model. The config I would like to see is something like "pinned". With this config I would like to see a number of columns to remain visible upon scrolling the table horizontally.
Request new features or modifications
If I understand you correctly, you can implement this yourself using our regions concept: https://www.bryntum.com/examples/grid/multiregion/
A grid can have any number of sub regions inside it which you can use to pin columns. Try it out?