Actually, Melchior did finished the sword in the original time line, since it was only due to the Prophet that he got imprisoned on Mt. Woe, and thus, didn't finish the sword on time.
Anyway, there probably was research on time, just probably something Gaspar kept to himself, or probably only let it be known to the other Gurus, considering Belthasar's Epoch. Some dialogue in Zeal do implies that Gaspar had been working on the TimeEgg/ChronoTrigger before the end of Zeal happened, so perhaps the general populace only knew vaguely of Gaspar's work, but enough to pinpoint a theme and stuff.