Your BE2015 install path was useful prior art for cracking the BE2012 (T-Mobile US, not Metro) variant — same chipset, slightly different blockers. Sharing in the spirit of reciprocity.
Full BE2012 installer up at https://github.com/dcherrera/n100-be2012-crossflash. macOS-native EDL flash (no MSMDownloadTool needed), plus a small binary patch to /usr/sbin/ofonod that fixes a SIM-init blocker which leaves Modem.Features stuck at ['sim'] on first boot — same modem firmware family, may be relevant to BE2015 users on certain SIMs too. README has the offset table if anyone wants to verify against their build.
Also confirms your "T-Mobile SIM works, Verizon SIM doesn't" observation on the BE82CB modem firmware — same outcome on our end, since the modem firmware is T-Mobile-band tuned.