good news, the Quan Chi bug shouldn't be devastating:
the buffs do not stack at all, it just resets it. even the duration gets reset.
Essentially, you have to land a buff on Chi, and then trance the opponent + execute the summon buff command on Chi.
the only unintentional side buffs this grants is:
-Being able to reset the duration of the buff (which doing it while the opponent is not tranced is very risky to do in the first place)
-If using non EX Skeletal boost, it allows you to change health or damage buff for the other one...if the roulette feels happy with you. There's always a chance you wanted damage, but you got health again, instead, or vice versa.
So, It shouldn't be game breaking, I assume.
I'm still going to take a look at this later, because it's really odd how NRS programmed the Skeletal Boost.