When you use this command the firework doesn't explode:
/summon FireworksRocketEntity ~ ~2 ~ {LifeTime:0,FireworksItem:{id:401,Count:1,tag:{Fireworks:{Explosions:[{Type:0,Flicker:0,Trail:0,Colors:[16711680,16740124,16771092],FadeColors:[16764784]}]}}}}
You can change LifeTime to 200 (~10s) but it still doesn't work...
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Numerical ids are gone, use this: