"Engage" vs "Is engaged"

[Otonashi]

It's... really just a vocabulary thing. I never had any issue with it.

[Ethikx]

This is one of the gameplay flaws I found. Your opponent can cast deep sleep on your units even if they are already engaged, etc. If a unit is already engaged, it should not be able to be targeted by cards that engage units. Another example is some SS are engage target unit, deal sp*5 damage to it. If you iczer attack with your unit, and activate that SS, I believe it should not be targeted, but it is anyway.

[Spears]

there is no 'and then' clause to deepsleep, you dont have to have a unit atall to use it. its working as intended, unless the ss states engage a disengaged unit then it will work.