Realistically I would say this frame is all done.
Any can be fixed given enough time, skill and money but some times it's just not worth it.
Both the cracks need to be fixed and it's tempting to think that one could sand off the paint, reweld/rebraze the joint, and have everything work out well. But this is so often just not the case and there are a few reasons for this.
First is that no matter how well you try to clean the area there will be dirt, paint, grease, degreaser, sand for the sanding.....etc down in the crack. To get a good strong joint it will need to be very, very clean and if any of this stuff is still in there the joint will likely fail once again. One way to be sure it's clean is to replace the tube - you open up the joint completely and clean it up like new and then attach a new and clean tube. But this is far in time and money terms from just rewelding/rebrazing the joint.
The second reason is that the joint failed the first time for a good reason.............one can't tell why from the photos of course but no doubt there was an issue with the original joints. It might have been dirty, it might not have had enough penetration, it might have gotten way too hot.............like I said - hard to tell by just looking. But really it's a moot point as the original sin still exists and the chance that one can rework something that was poorly done to begin with and have it turn out OK is really small.
If there is a warrantee involved I'd be looking at that - if not I'd limit my losses and move on.
Sorry for the downer but I need to spell it out as I see it.
Dave