Question

How to set up Script Recognition for the checkmark group if the standard recognition does not work well?

Answer

You can switch to the Script recognition on the Recognition tab of the checkmarks group field's properties:

Used FlexiCapture script objects:

https://help.abbyy.com/en-us/flexicapture/12/developer/icheckmarkgroupvalue

https://help.abbyy.com/en-us/flexicapture/12/developer/icheckmarkvalue

https://help.abbyy.com/en-us/flexicapture/12/developer/ipictureobject

https://help.abbyy.com/en-us/flexicapture/12/developer/ipictureobjectsinfo

Here is the code snippet that recognizes the checkmarks based on the BlacknessPercentage property (what part of checkmark area is black):

int threshold = 25; //% of black pixels

for (int i = 0; i < Result.Count; i ++) //we iterate through all single checmark's rects
{
    int left = Result[i].Rect.Left - FieldRegion.SurroundingRect.Left;
    int top = Result[i].Rect.Top - FieldRegion.SurroundingRect.Top;
    int right = Result[i].Rect.Right - FieldRegion.SurroundingRect.Left;
    int bottom = Result[i].Rect.Bottom - FieldRegion.SurroundingRect.Top;
//calculate the coordinates of a single checkmark in the whole checkmark group region

    IPictureObject oneCheckmark = FieldRegion.Picture.CreateEditableCopy().CutOut("[" + left.ToString() + "," + top.ToString() + "," + right.ToString() + "," + bottom.ToString() + "]");
//cut out a single checkmark area

    if (oneCheckmark.AnalyzePageObjects(null).BlacknessPercentage > threshold)
    {Result[i].Value = true;}
    else 
    {Result[i].Value = false;}
//compare the % of blackness in the single checkmark area to the threshold
}

The scheme, how the Result[] and FieldRegion are related: