there is no possibility to shift the icons displayed directly on the map from a KML file, there is however a system parameter that supports the reference position for their display but this affects all POIs and speed cameras

[poi]
force_center_poi_icon=1

each icon is either drawn from bottom to top on the geographic position or the center of the image is adjusted to the position.

In this second configuration, by drawing a layer centered on the position, all you have to do is draw the desired image in reduced size in the frame, which will give the appearance of the desired shift according to its placement on the layer.