You know? on 2nd (3rd? 12th?) read- it IS a little ambiguous. I may even be leaning toward your interpretation, TBH.

It all 'hinges' on the sentences before the one you quoted:
"...as well as a teamwide debilitation.
Force Reduction
Reduces maximum team size by 1.

Ouch. That hurts. But do the Tactics make up for it? Survey says... you bet."

That makes sense, as a -1 to team size hurts. Six becomes five, Five becomes four, etc. It's the phrasing of the start of that sentence "...teamwide -1 armor and -1 health debuffs..."

"Teamwide" does seem to indicate your team, not your opponent's but as you say: It's all theory until we see the card release or get some clarity from the team.
@clayboyn