Did you have AGB_FIRM modified on Emunand before downgrade? Not sure if that would have any effect. It should only cause downgrade to 2.1 to fail with error. My advice to people is to not downgrade their current EmuNand, but to backup their current EmuNand, write SysNand to EmuNand and start from there. That is of course assuming your SysNand did not have modified AGB_FIRM or TWL_FIRM installed. If that is the case you need to "update" to 9.2 again with sysupdater 0.4.2 to fix the modified CIAs