The reason volcanic ash is so hazardous to engines is that once the ash cools, it turns back into sand/rocks and bangs into fan blades impacting engine performance. Smoke doesn’t have quite the same risk - it’s more so the visual obscuration of the cockpit.
The pyrotechnics itself aren’t a major hazard (risk of fire is low, and the turbulence from the explosions is minimal), but flying a commercial aircraft (whose pilots may or may not have stunt flying or military experience - we don’t know) that close to a public building with 50,000-60,000 fans is for sure a public safety hazard.