Jul 3, 2021, 11:4107/03/21
She is supposed to give heals of 20.92 percent of her HP when fully booked, which is 11 616. Not quite sure why she would do marginally less in your case.
But as for 27k heals, no, that's you misunderstanding her skill. Increases for heals are like increases for damage - when it says +5 percent, for a basic heal of 15 percent of HP, it means that it increases from 15 percent to 15.75 percent. It's not a 5 percentage point increase from 15 to 20 percent.