When this lvl 9 happened 2-3 years ago it was bugged then got fixed for the two bugs it had.
Apparently the bugs are still present because the lvl 9 does not perform as it reads.
Here are the links to the old reports since the bugs are the same.
Ninth Sister lvl 9 Revive | EA Forums - 11040658
This Revive I just confirmed it again.
Ninth Sister Datacron Bug | EA Forums - 11038144
This one I don't have confirmation for but my bet would be it's also bugged and the stat bonus just goes away.
EA QV TeamThe first issue had a localisation update and description was updated to match the actual functionality.
The second issue was related to +200% Max Health expiring at the end of the turn, rather than at the end of battle. This was fixed and is working as intended
At the start of encounter, all Inquisitorius allies have +200% Max Health and are immune to Ability Block.
Ninth Sister deals 20% bonus True damage based on her Max Health with her Basic ability if the target enemy is inflicted with Purge.
If any enemy has 6 stacks of Purge when Ninth Sister is defeated for the first time, she consumes all stacks of Purge from a random enemy with 6 stacks of Purge, recovers 100% Max Health and Max Protection, and removes 50% Turn Meter from all enemies.
This is the description we have in game right now, so maybe the code was updated so she revives then heals but the description is way different than how it actually works.
EA QV TeamWe asked to update the description to match functionality