At least the damage to the top and down tubes is easily seen so you can keep an eye on it and tell if the damage is getting any worse. Since you're not in a position to replace the frame I would suggest at least making a very careful examination of the fork and steerer tube (i.e. take the fork out of the frame) to inspect for any damage there. I've experienced a catastrophic failure of a steel steerer tube and would not want to repeat it.