It should not be imbue-able if that is the intent, and the damage is still included for items like Focus Lens. The problem is that using the ability does not trigger Mystic Reverb at all, it should either be triggering Reverb or it should not be an imbue option. It is objectively broken in its...
What an articulate little guy! Either the item should apply damage or it should not be able to be imbued on Soul Exchange. There is objectively a problem that should be addressed.
It appears that the damage type of her ultimate has changed. It originally appeared to be functionally "True Ability Spirit Damage" meaning it bypassed all resistances etc, but now it's showing up as orange damage and is no longer proc'ing ability/spirit damage proc items.
Lady Geist's ult does not trigger mystic reverb even though the item can be imbued on it. This is a new bug as the combo has worked for over a year at this point before now.
I believe reverb is intended to proc on the first enemy it hits, then it goes on cooldown. This is also why reverb on bomb is liable to get wasted on the dot ticks on minions.