I agree with you that you have to slide the month prior to knock out a TRIP with vacation. And I agree with you that you should have been able to slide your vacation days to the left and knock out the carryover R days.

But, it sounds like you elected not to do that, which is a choice. From the company's perspective, they want the carry over R days to allow trip assignment from the Sunday prior. So, what you effectively requested is an un-ueseable R day on that Sunday, or an R day they'd wind up paying overage on if they did use you.

To me, sounds like you kind of wanted the time off at the beginning of the month, but, the time in the middle of the month was the priority. And, I understand your irritation at not having your request honored. But, there is nothing that requires the company to honor your request.
And, again, the company built the JAN R day C/O lines with the expectation of a trip being assigned to carryover into FEB. So, really shouldn't be surprised that CRS has guidance to protect that interest