These panktis bring back fond memories...
1] In the first pankti, Bhagat Ji has used an analogy of sesame seeds to the human breathes. If he knew he had very few swaas left, he would have been more careful and used them wisely. By using them wisely, he means he would have spent more time in simran and kirtan.
har japadhiaa khin dtil n keejee maeree ji(n)dhurreeeae math k jaapai saahu aavai k n aavai raam ||
Do not hesitate for an instant - meditate on the Lord, O my soul; who knows whether he shall draw another breath?
We live in the hope that we will die when we are in old age, however this is a misconception. We don’t know when we will draw our last breath, so we should not waste time.
Second shabad could be about how Vaheguru admires people who adopt humility, and this is a virtue we often ignore, especially when we progress spiritually.
2] I always used to understand this pankti to mean 'don't write black marks in your own karma'... If you understand yourself to be wise, and intelligent then you must be aware not to commit any bad karma. Instead look within yourself, and remain humble.
However, this translation you've given seems to make a lot more sense. We all have a tendency to highlight other people’s faults, and sometimes it results in nindiya. Maybe we should look at our own jeevan, and be humble.