This is a limitation of Philips DICOM images, not dcm2niix. Please see the dcm2niix notes. With the contemporary Philips DICOMs it is impossible to compute the FSL/BIDS definition of TotalReadoutTime. For the details, please see dcm2niix issue 377. Please lobby the Philips clinical scientist affiliated with your site to include additional sequence details in the scan.
The good news is that the “TotalReadoutTime” correct is not critical to the TOPUP correction if the readout time is identical for all the relevant images.
The order of j and j- does not matter: the final transform will be of identical magnitude.