The problem is that they never (not even during Sento's explanation) did they say that the tree was planted to cure Latifa. The tree uses Anima to bloom, so if it consumes a significant amount it would even be counterintuitive. Sento's explanation more or less said the tree was a Litmus test for Animus accumulation, and Animus counters the curse.

It's all pretty unclear about what actually happened. Do the petals themselves, presumably a converted Animus, have the curse-countering effect? Or were they solely a proxy showing how much Animus was in the air?

Was the curse lifted? Or did the tree's bloom (assuming this is the answer from ^) counter her "reset" this time round? If the latter, Kanie will have to do this yearly.