Excellent! Glad it works!
Eco2 is written to if either Draw All Outlines is selected or if Outline Thickness is non-zero.
(in all fields, blank and non-valid data are interpreted as zero).
If Outline Thickness is non-zero, then pad outlines and text strokes are drawn that are being checked. The silk to pad check first determines if the text box is close to the pad. If so, then each individual stroke is checked. Those strokes are drawn on the debug layer (currently hardcoded to Eco2) if Outline Thickness is non-zero.
If Draw All Outlines is selected, then the Silk check draws all pad outlines and all text strokes on the debug layer.
Incidently, selecting Slow Check will check against text strokes, while unselected will only check text boxes.
Text strokes, in case it isn't clear, are the individual line segments that, combined, create the letters.
I hope this helps!