I am not one hundred percent certain if the trait is functioning, or if the tooltip is inaccurate, however I feel its worth mentioning that Cleansing Water does not work on application of Regeneration but on applying the base Regeneration stack.
I tested this and I found that when I was the only carrier of Regen, and I was applying Regen freshly, conditions were being removed. But when I placed Regen over an active Regen boon, no conditions were removed.
As I read the trait, it implied to me that the removal would apply to any regeneration applied by the Elementalist. If its working as intended, it’d be helpful to have the text altered to improve the clarity.