It is indeed whooping slack of 60 mins in total.. u mentioned about KR only- 20-30 mins that actually 40-50 mins slack and the slack in CR is 10-20 mins, in total it is 60 mins.
If it was able to screw trains in down run, still got delayed then the reasons for kudal delay is just rainfall, the 120 mps was restricted to 110 kmph due to rains... still being 55 mins late at Kudal and arriving KRMI just 8 mins late, @110 mps confirms the 55-8=47 mins slack in KR and in CR too there is evident slack.