I personally feel like all 3 healers are generally quite balanced at this point in time, more so than they've ever been.

Astrologian just needs some QoL stuff like better mp efficiency (seriously, aspected benefic is horrific in terms of mp efficiency compared to similar abilities), and a Ruin2-like ability to make using their million off globals feel less janky. Ewer/Spire could be combined into a single card for all I care, if that's what it takes to even further reduce the chance of getting cards that are complete ass.