I just tried quickly with the .Z80 snapshot of the first part of The Archers, and the file on that site does seem corrupted: it loaded into a Spectrum emulator, but the graphics were all messed up, and L9Cut couldn’t find game data in it.
The site does have .TZX tape images, though, which look fine. You can’t use l9cut directly on those as they are images of the data on the original magnetic cassette tape, rather than a dump of the Spectrum memory. But I loaded the .TZX tape image into a Spectrum emulator, saved out a .SNA snapshot of the memory, and l9cut was able to extract the data fine from that. So it is possible, just with a bit more work.
That they are multiple choice games rather than parser doesn’t matter in this context, the format is still the same as used by all the other Level 9 games.