You said they were not convicted of "failure to report." I posted the charges for which they were convicted for exactly that alleged act.
Compean was also convicted on Count 7 which included "picking up brass," as you call it. No such charge was ever brought against Ramos.
Here’s the thing: you don’t understand what the word “charge” means, in a legal sense. Ramos and Compean were not “charged” with failure to report, they were “charged” with tampering—with evidence of failure to report supporting the “charge.”