A better way to refactor this would be to have two functions:
getCallSiteInfo() => returns (lastSparkMethod, firstUserFile, firstUserLine, firstUserClass)

formatSparkCallSite() => calls getCallSiteInfo then returns the formatted string

you can replace the earlier references to getSparkCallSite with formatSparkCallSite, then for the new cases you added here, you can just call getCallSiteInfo and you only use the firstUserClass and ignore the other stuff.