@mr_creator said:

Next I need to move everything to the origin of global coordinates.

This line of code will create a new group at the origin of entities. If this is the top level model's entities, then this is the global origin. If it is some other component's or group's entities, then it is their local origin.

@mr_creator said:

group1.transformation.origin have zero coordinates, but group1 is not at zero.

This confirms then that group1's origin is at the origin of the active edit context's origin.

Just tested Sketchup::Text#set_text on SU2020 and it (as Dezmo says) does not display the change until the view is redrawn. So Sketchup.active_model.active_view.invalidate is necessary to see the change.

I'll open a documentation issue for this "quirk".