How to create below type of imposition with automatic Press Sheet Size in FFcore where x and y are margins and those margins should adapt depending on sheet size and can't be smaller than x=2,5 mm and y=3,5 mm?
This layout can definitely be done. Use the following settings in Gutters
The margins may be larger than the distances specified but they will not be smaller.
FFCore will not select a press sheet size if it would cause smaller margings. Instead it will select the next larger press sheet size or if there's no larger press sheet size it will fail the job with an error.
To rotate the left column, use the Column Transform Mode (on the top, right corner of the preview).
One caveat: The "Transform Modes" are not available if the number of rows and columns is automatic.