The error is clear in the first two images. The syslinux.conf or extlinux.conf is configured for boot=LABEL=System and disk=LABEL=Storage and those partition labels do not exist on the boot device. It should be using boot=UUID=blah something like belo
This is only partly true for x86 systems, as it turns out. The installer itself will use UUID, but the installed x86 system will use LABELs.
The x86 installer will create the two partitions and file systems on the x86 client, and then label them "Storage" and "System", before creating /flash/extlinux.conf with LABELs and - if UEFI support is detected - copying /flash/extlinux.conf to /flash/syslinux.cfg and /flash/EFI/BOOT/syslinux.cfg. Copying both syslinux.cfg files ensures that a UEFI-capable client will boot successfully using either legacy BIOS or UEFI.
So MacNB's syslinux.cfg using LABELs is correct.
Assuming the problem is the drivers being loaded as modules, there is now a test build available (based on LE9 with Kodi 18a1) that includes in-kernel drivers.
MacNB can you manually upgrade your SD card by copying the KERNEL and SYSTEM files extracted from the test build tar file, then try booting your newly updated SD card and report if it works or not.
Edit: I see mglae has posted above - if you want to play it safe, use a fresh SD card based on an official disk image and then manually update the KERNEL and SYSTEM files in the root of the first partition using the files extracted from the tar file, before booting from the SD card in your client device.