Absolutely and it absolutely should be more intuitive. In the meantime the easiest way to understand it is to have your own pay sheet side by side with theirs. Start by writing down or using a spreadsheet to show your original awarded line along with each trips value. As the month goes on through IOT and DOT catalog every swap, drop, and add along with the value of the new trip. This way you have a constant working tally of what you will be due at pay day. Also if something seems fishy you will be able to see what you swapped for even if you traded it four tikes before flying the trip you flew. Also, keep track of your block times during the trip if it's a hard time trip and move the final value to your personal pay sheet once the trip is completed. If you have a trip modified with a letter at the end make note as to what changed and to whether you are protected to the original value or if the new trip is worth more.

I've done this at every company I've worked for, even the ones with intuitive pay systems and it's worked pretty well. I come here for one reason only and that's to extract as much money out of this place as possible for myself and my family. Taking a few minutes a month to do my own personal pay tracking seems like a small time investment to me.

The point still stands that their system should be easier to understand.