It's always great for me to see people take an interest in the forums I moderate. I tried once before to get OW active, but it didn't work, and I was stuck on how to fix the lack of activity in that section. (I also know that you've been trying, and believe me, I love what you're doing!)
Before there was a "Poem of the Month", way back before I became moderator. And it was the same idea you have, where a prompt would be given and people could write poems based on that prompt. There wasn't any recognition for those who participated, so interest waned. However, since now there's the emblems in place, then the idea might work better because recognition can be given
So I'm definitely on board with this idea.