Seems like in order to be a competitively viable character you need some moves with very low lag (starting or ending): Joker, Snake (grenades), Pichu, Peach, Pikachu, Lucina, Wolf, Palu. Zelda has, let's just call it generous amounts of lag.
The trade-off seems to be that if you have lag you can survive a long time (heavy) and kill easily. Intuitively this does not sound like Zelda - she feels light, and killing is difficult because she is slow and her best kill options require small sweetspots, hard to hit against the best fast-moving, small-hurtbox characters.
They cannot possible think that Joker is balance while also thinking Zelda is balance. I am fine with Joker being powerful - I want to play a powerful game - I would just argue that Zelda (and others frankly) do not compare and need significant buffs in order to do so.
Consider:
Zelda is lighter than Joker (lighter than Peach even).
She's slower than Joker (run, walk, air, fall, fast fall).
She cannot wall jump while he can.
His multi-hit up-air drag down confirms into smashes, hers does not confirm in to anything.
His grabs are must faster on start up and have less end lag.
His counter starts on frame 3, her's on 11, though hers only lasts a max of 22 frames and his last over 2 seconds. He can act faster out of his counter than she hers.
Eiha comes out on f16, deals 13.2 damage. Din's fire comes out on frame 44 and deals 4.2 or 8.4 if you sweet-spot it.
So she is lighter, and slower, and weaker. Something needs to change.