What happened to the gold?
Solution 1:
No, there's no mention at all of those events in BC2. It is the same group, however, it seems DICE just wanted to make the audience forget those events. Makes sense as back in that time they were looking for innovation, and to involve people in the series without previous knowledge.
One can assume they got caught and had to do more work. I don't think they got any kind of wealth as Sarge is about to retire. Had he had money he wouldn't be the Sarge we got to know in BC2.