Neither the change to iMac18,1 nor the ig-platform-id/device-id spoofing are showing in this IORegistryExplorer file.
Make sure you are booting from the correct EFI partition.
My edited EFI is on disk0s1, which I thought I was booting from, and appears to be on the Samsung evo 1tb. It is however booting from disk2s1 according to EFI mounter v3. It only offers these first 2 EFIs you see here. Somehow disk0s1 and disk2s1 have become dissociated although they are the same disk. This explains why the configurator never let me mount that partition, I've been using terminal to mount disk0s1. But it is not possible to boot from it.
/dev/disk0 (internal):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme 1.0 TB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk2 1000.0 GB disk0s2
/dev/disk1 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *2.0 TB disk1
1: EFI EFI 209.7 MB disk1s1
2: Apple_HFS Crucial 2.0 TB disk1s
/dev/disk2 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +1000.0 GB disk2
Physical Store disk0s2
1: APFS Volume Samsung 14.7 GB disk2s1
2: APFS Volume Preboot 45.4 MB disk2s2
3: APFS Volume Recovery 517.0 MB disk2s3
4: APFS Volume VM 2.1 GB disk2s4