I don't think you can be sure until you see the long term results. I suspect that many chickens have bumblefoot (undiagnosed) because no one looks at their feet. I was in a panic last year when I operated on my EE's feet. She still has small spots a year later, but she seems to be doing OK in spite of the thing. WE got past the acute condition and now it is more ongoing. I suspect she will eventually die WITH it rather than FROM it.
Good luck. I would probably take another shot at her foot, too. Some of the infection may be from the damage done by the initial injury that was made worse by existing bumblefoot infection.
As a continuing medication, I spray my chickens' feet a couple of times a week (after they are on the roost) with Vetericyn Wound % Infection Care (the liquid, not the jell). It isn't cheap, but our local farm store has it at the same price as Amazon (~$30) so I don't have to order it (for the 16 oz spray bottle). The other advantage is that the stuff works on my Golden Retriever's hot spots.
Sharol