For now there is no hint support for each node. However this post specifically implements hint support in a descendant class and dynamically retrieves it. The code shows how to set properties, but the code could be adapted to handle hints dynamically
Specifically this code snippet is called dynamically when hovering a node, so you could write code that retrieves the hint dynamically instead of via property.
function TAdvTreeViewHint.GetHintString: string;
if Assigned(FHintNode) and Assigned(FHintNode.Node) then
Result := FHintNode.Node.DataString
Result := inherited GetHintString;