while assessing my own Spectrum hoard I came across an undumped version of the Multiface 128 and then across a set of diagnostics while trying to get some of my stuff going.
Unfortunately, somewhere between 0.226 and current the Spectrum driver broke. While in 0.226 BASIC loads without problems, in current top of GIT, MAME exits with what looks like a memory error.
Trying the newly added diagnostics ROM, it proceeds a little further and then fails at a different RAM address.
I've issued a pull request for the addition of the ROMs mentioned above.