I do not have access to a Siemens XA30. Several of these your warnings appear to be inherent to the conversion of low quality localizer ("scout") series, which are only used for planning subsequent scans and are not required for any analyses. In general, I do not export localizer scans off the console. However, you can use the dcm2niix feature `-i y` to ignore (not convert) these files, which will eliminate many (perhaps all) of these warnings (NIfTI requires all slices in a volume are co-planar, which is not the case for localizers).

If this does not fully resolve your issue... I can not provide further insight into any residual errors without seeing a DICOM dataset that elicits the errors. Feel free to send a link to a zipped dataset directly to me. Alternatively, dcm2niix is open source, so you are free to fix the error yourself and submit a pull request to Github. As my center will eventually be upgraded from VE to XA, I have a vested interest in seeing support for these systems improved.