Although you mention defaultModeChangeDelay at line 146

unsigned long horusSecondTransmissionInterval = 0; //set to 0 for default delay (defined in defaultModeChangeDelay), otherwise will deterimne delay between first and second Horus transmission

it is nowhere defined in the current code.
It used to be

unsigned long defaultModeChangeDelay = 0; //in milliseconds, 0 - disable, 0<delay<2000 - standard delay, 2000<delay - delay + radio sleep mode and recalibration (if radioSleep enabled); default delay between radio transmission modes