Tag Team should reset the cooldown of Quinn's Vault
Yes it's a buff, and yes I feel it's needed.
Quinn has long Cd's so players have to use them cautiously(especially vault), and decide whether to save it for ult or not, because without that Cd up she can not properly perform her tag team-gap close combo.
Seeing as harrier passive is disabled during tag team, this would not be as much a damage buff as a utility buff. This will provide Quinn more freedom to use her vault in human form normal trades while still having the gap closer initiation from tag team ready on demand.
E.g. If Quinn currently uses vault to engage and bring her target low with a few auto attacks, she is much less likely to secure the kill with tag team without vault to dash.
If Quinn tried to save vault for tag team, she'd be less likely to bring her target low enough for a safe tag team combo.
If tag team reset vault, she could use vault in human trades, and have the needed dash to get in melee range for tag team action.
This also means Quinn could tag team-vault to a minion/creep on demand for an escape.
P.s. Her secondary role title should be changed from fighter to assassin because she obviously deals more damage then she can take, and fighters are more of a brawling extended fight type, and assassins, well they assassinate which is more like Quinn's style.