Lava according to the wikipedia is usually between 850 and 1200 celsius, bronze melting point is 950 and copper is around 1085 celsius, tin is like 280 or something idk, low af.
I can understand the argument that maybe it's not enough to actually make bronze (Debatable, is all lava in haven cool af or what?), but it should be able to at least make bronze nuggets out of a bar, especially if you take it out of the heart of a volcano.
Iron melting point is too high at 1500, but bronze should be doable.