Online Google maps location has offset

Hi, First of all, thanks for your great FREE APP.
When I use Online Google maps in China, I am sorry to find that all the locations have some similar offset, about 500 meters away from my actual coordinates. This also happen when viewing my saved tracks in online Google maps. And the longitude and latitude offsets of all locations seem to be a fixed value. But when changing online map to Google Earth, everything is OK.

Can you check it and help to fix it?

Or can I adjust it via modifying the onlinemapsources.xml content?

<url><![CDATA[http://mt{$s}.google.com/vt/lyrs=m@121&hl={$l}&x={$x}&y={$y}&z={$z}]]></url>

Can I fulfill it just like this?

<url><![CDATA[http://mt{$s}.google.com/vt/lyrs=m@121&hl={$l}&x={$x+offset_longitude}&y={$y+offset_latitude}&z={$z}]]></url>

Or how can I do so?

Looking forward to your help.

Best wishes!