On GNUBG's discussion about EPC (
https://www.gnu.org/software/gnubg/manual/html_node/What-does-epc-mean_003f.html), the example of 5 checkers on the 1-point and 4 checkers on the 2-point is a typical 5-roll position. Therefore, it appears to be an error to say that the expected number of remaining rolls is 2.189. A 5-roll position is elsewhere calculated to be an EPC of 36, not 17.878. So unless I am missing something this seems to be a mistake.