Sona buffs could easily go to her auras

The big problem everyone had with the Sona rework upon launch was the change/arguable outright removal of her auras (I'm not sure if one-off effects can really count as auras, more just short team-wide buffs). People liked the permanency of her old auras and also the fact that in a team fight they would actually apply to the whole team.

I don't ask for the old auras back because I do see value in the current ones - empowered autos are cool, shields are cool, and E is a mini Sivir ult which is nice. But even some very modest buffs to her auras would help them feel like a bigger part of her kit that are also less frustrating to use and less punishing to use incorrectly (primarily speaking about W here). Some will say that Sona is quite strong, so while the buffs I suggest are definitely buffs (probably most notable on E), I've chosen changes that will make her FEEL a lot better without actually doing too much for her power level.

General change: Aura range increased from 350 > 400. This is quite honestly a tiny change but it still matters - for one thing it means it's physically possible to get everyone within your auras without your entire team taking a Malphite ult to the face. This change would make it so that Sona would have a slightly less irritating time trying to position herself so that she can provide buffs to teammates without also taking thousands of damage to the face.

Hymn of Valor: This is the only aura that gives an effect that can last for a large part of the aura's duration, so it's pretty close to fine imo.

Aria of Perseverance: Shield duration increased from 1.5 seconds > 2 seconds. Most support shields are very forgiving, lasting 4+ seconds. Sona's shield on the other hand is very unforgiving. The chances of getting maximum (or any) damage mitigation are small unless you use it once a trade already starts, and support shields tend to be used to avoid the start of one more than anything. Sona's shield value is quite small (155 + 20% AP at level 16) and for that reason it's unlikely that in a team fight scenario it's not popped before 2 seconds anyway (so this isn't a massive buff), but increasing the duration helps reduce the "wow there was literally no point in shielding there" feeling, as well as making it more obvious to teammates that Sona is actually doing something because the shield won't disappear before they even notice it.

Song of Celerity: Team movement speed buff duration increased from 1.5 > 2 seconds. Too often using E ends up with Sona outrunning her teammates and having a really awkward engage pattern. Increased aura buff duration would help reduce this frustrating feeling. Sona will still be moving faster than her teammates, but at least they have an extra half a second where they can vaguely keep up with her.

tl;dr:

Aura range 350 > 400 Shield duration: 1.5 > 2 seconds Speed boost duration: 1.5 > 2 seconds

If base values/ratios need to be discussed then they can be, but I think even a slightly bigger aura range and a feeling of at least SOME lasting effect on her auras would really make Sona feel more satisfying to play, while actually doing relatively little to increase her power.