The way geolocation works will be 100% dependent on the user's web browser. The only thing the plugin can do is ask the browser "give us your current location" and the browser returns their BEST GUESS as to your lat/long. Every browser is different based on the operating system, device, user settings, and more. It is far from a perfect system but is also out of our control. Too many website builders are trying to skip building a custom mobile app by using a web based map. Web based maps will never be as accurate as a true mobile app until/unless the browser community agrees to a proper geolocation standard.
If you want accurate geolocation services, which only makes sense on a GPS enabled device and thus indicates a mobile-centric offering, you really need to considering building a proper mobile app. Store Locator Plus has hooks to make this possible so your web-based store system and mobile app data are in perfect sync, however you still need to go through the effort of building a mobile app.
As for import, the system does work if your data is formatted properly and the addresses are accurate and can be located by Google. I will get to the sample CSV file that was sent to check for bugs on the import but every single CSV I've received since last December has been a problem in the CSV format NOT the code that imports it. I will get to that file EVENTUALLY.
As far as I can tell, bulk import and geolocation are working properly.