I downloaded the KeyswitchExpressions file and tried to load them as a library. I get an error message (Error ID=-12). It appears to be a Finale file, but I get the same error code if I try to open it.
Scroll dwon to where you see the keyswitch plug-in reference.
(It's mistakenly labelled a plug-in. it is not one)
There's a link labelled "keyswitchexpression.mus". Either click or control click on that link to download a complete finale file with the expression library built in.
If that doesn't work, directly under that link is one that says something like,
"try this one" I don't remember the exact wording. Control click on that link to download it. It should download a text library file. Open a finale document, click load library, scroll to the folder you downloaded to, under type of file select show all files. Then select this file to load into your document. The check the text expressions in that file to see if the new ones have been added.