nm, i found my workaround:

mvm -f c:\path\to\pom.xml exec:java -Dexec.args="importfiles -account 123456 -otherparams -paths '/SuiteScripts/my path with spaces.js'"

my favorite issue of this type was a mac user uploading a file with "|" in the name, which NetSuite's file cabinet allowed, but windows will not

When I get back I'll see if I can't

sdfcli importfiles 'file with spaces.js'