This requires a lot of unpacking.

1. Were there snipers targeting civilians from the top of the hill south of Sarajevo? Undeniable, that was never debatable.

2. Was he present at that hill around the time snipers were shooting at civilians? Yes, he never denied being present there and that's where that one grainy video originates.

3. Were there rich foreigners on that hill doing "war tourism" or were all of the civilians shot by Serb forces exclusively? Up for debate, enough evidence to start some investigations, highly unlikely that those investigations will be able to say anything conclusive over 3 decades after.

4. Did he play any role in making those deals with rich foreigners? No evidence of that that's more concrete than putting him at the right place at roughly the right time.

So, him saying that he heard any sort of foreign language around him would be the evidence of #3, but him legitimately not witnessing any such thing (and everyone believing him) wouldn't really be the evidence of the contrary, as #3 could've happened before or (more likely) after his time on that hill.