Himora was already invaded by the Amhara government so this was out of Susan’s control. They were planning to invade western Tigray for years.If Sudan really invaded Ethiopia, there would still be corridor to the Tigray Region.
Egypt messed Sudan up by allowing Afwerki to tilt the scale in favor of Amharas while [Egypt] pretending to be on Sudan's side.
Egypt didn’t get involved in the conflict (at least not yet). They offered and the Sudanese military viewed it as unnecessary for the time being, not to mention the military never bought heavy weaponry to the border region. They were able to kill hundreds of Ethiopian soldiers and Amhara militia only with basic guns and Toyota pickup trucks.