Hi Will,
I would have thought that would work - at least the general approach you're taking. The Mulitsample is expecting an array of file names in the Sample parameter. The file names should be space-seperated. If file names need "calculating" they need to be enclosed in curly braces, like {'pottery break 1.aif' sampleFileNamesInSameFolder}
I've just tried the following set and it works for me in the Multisample Sound:
Maybe one of your files names has a typo in it? Try it with a smaller set and see if that works. I think it should.
Does the last file in your list, before 'pottery break...' have a comma in the name? ("...Glass:Bow C4,2.aif"). Should that comma be there?