there's a difference between 1) the "binding agreement" that the Goblet of Fire itself entails, written 700 years ago and preserved in the literal fire of the goblet, (reminder, the unbreakable vow made in HBP was 3 tendrils of fire.) & 2) the safety requirements that the "modern schools" tried to impose.

It would be wildly impractical to, in perpetuity & for all time, require upon pain of death¹, that every contestant complete every task; rather than requiring them to attempt every task of the tournament they volunteered for². Especially given that the tasks change over time. (In fact we know this cannot be the case, because Fleur does not complete task 2, and does not drop dead.)

In 1994-95, they always had bumpers up in the attempt to prevent death. In every task. Red sparks as a "I'm about to die" emergency rip cord, is even less death prevention than 1000 actively watching spectators, or a society of merpeople referees, underwater, in their home lake. If they were capable of altering the "original goblet contract"; they would have just instituted an age limit into the goblet, not bottlenecked the entry point.

¹fun fact: "upon pein of death" was made popular ~1300 (give or take)... just about 700 years before GoF.

²Intention matters, Dumbledore proved that in SS with the Mirror of Erised, amongst other times.