Synesthesia on a success says target has Clumsy 3 for 1 round. Does that mean after the round is done the spell is completely gone or does it countdown to Clumsy 2 the next round and then Clumsy 1, then the condition is removed?
I believe the creature would be Clumsy for the duration of the spell, so in the case of a success on the save, it would be for 1 round, then clumsy is entirely gone.
This differs from the Critical Failure result, wherein the creature is Stunned 2 in addition to suffering the other effects of the spell. That condition would count down as normal.
The affected creature would be Clumsy 3 for the entire duration of the spell, based on how well they made their saving throw.
Most status effects do not have a countdown mechanic, it just happens that sickened and frightened, two of the most common conditions, do.