procedure TP_GlobalHandleClass (HClass:TClass;Handler:TTranslator);

This procedure makes it possible implement another translation handling of a class than what you can control with TranslateProperties(), TranslateComponent() and the TP_* procedures. For instance, if you create a new class that does not use the published keyword, its properties cannot be iterated by TranslateProperties() and TranslateComponent(). Another example is, when you get 3rd party components, that fail when you translate it's properties, but if you do something special to them, they translate well.

Basically, if you cannot translate a component using TranslateComponent, but you can write a procedure yourself that can, then use TP_GlobalHandleClass to make TranslateComponent use your procedure.