No, that's not correct. You should have as follows.
Code:
$user->set( 'name', $form->data['navn1'] );
$user->set( 'cb_cell', $form->data['mobil1'] );
$user->set( 'cb_adresse', $form->data['adresse1'] );
$user->set( 'cb_postnummer', $form->data['post1'] );
$user->set( 'cb_birthday', date_format( date_create_from_format( 'd/m-Y', $form->data['foedsel1'] ), 'Y-m-d' ) );
$user->store();
Yes, you still need to do the store.
This assumes you want to add those values to the CB users profile data. Your previous usage on page 1 is the opposite so I've no idea your intentions. set will set a value to the object and get will get a value from the object. Base off page 1 code you'd have the below.
Code:
$form->data['navn1'] = $user->get( 'name' );
$form->data['email1'] = $user->get( 'email' );
$form->data['mobil1'] = $user->get( 'cb_cell' );
$form->data['adresse1'] = $user->get( 'cb_adresse' );
$form->data['post1'] = $user->get( 'cb_postnummer' );