how come we've managed to create temperatures upwards of 5^12 at CERN but haven't melted/destroyed the surounding area?

Temperature is a measure of total energy of the system. The temperature that you discuss is really just an extremely energetic but very tiny mass, so the energy, if released to the surroundings, would rapidly dilute (way more cold mass around so the average energy per unit mass would become fairly low fairly quickly with distance from origin). It would be a major problem if the energy did get allowed to continuously bleed out into the surroundings, but then it would be effectively impossible to achieve the extreme temperatures in the point location. It would consume too much energy in the effort.

You are talking an atom here, and that heat energy was radiated and gone in milliseconds.

The temperature is confined into a very tight beam, and it's magnetically confined. The number of particles circulating are measured in the femtograms, so there isn't a lot of particles achieving those temperatures. In actual fact, all of the particles circulating around are only enough to heat a cup of coffee.

Temperature and heat are two different aspect. For the damage, we need heat. This temperature convert that into heat per particle then you may find it not sufficient. If you put your hand, it may get frozen.

Those temps were *very* confined to a *very* small volume, for a *very* short duration... The longer a temp like that would last, the more damage to the surrounding area it would cause. I believe the highest melting point of a known material is about 6200 degrees F; so - anything *that* hot or hotter is going to cause damage if the heat persists.

It's mainly because only a few atoms were at that temperature. A tiny bit of energy, concentrated on a very very tiny amount of mass. The total energy was drowned out by the billion time billions of atoms at regular temperatures.