Would it be a good idea to have those 3 orbs floating around Syndra only showing when her ultimate is available?
It would be similar to how Ekko has his trail. It would offer somewhat counterplay to her burst potential as the other player would be able to judge his trading prowess better against her.
That's not a QOL change, it's a nerf.
Is it a good nerf? Debatable. Displaying ultimate status to the enemy in a way outside of player skill tracking CDs is a situation changer. In the end, Syndra players already behave very defensively without their ultimate because of its vital necessity to winning trades. Knowing, and keeping track, of this pattern offers potent skill expression to engaging with her. The best case scenario, as you say, is for the enemy to judge trading (or, often, out right kill potential) against her. As her whole pattern revolves around defensive denial during the cooldown, it may ultimately not achieve much of anything for either party.
Ekko's ultimate behaves the way due to needing to know where his damn rewind clone is, since it can crop up anywhere at any point. Otherwise, you run the risk of training people to walk into it in order to fight him. There's more immediate impact to his rewind mechanic than a simple GFX effect on a model.
Edit: For further thought provoking, consider the readiness of ones like Veigar, LeBlanc, and Ahri, who all maintain relatively high damage thresholds against squishy targets in very fast situations. Syndra's ultimate is dictated by the number of spheres on the ground, so she actually displays her threat rating much more visibly than they do.
Not until they rebuff her ult back? The ult nerf was unnecessary anyway..
