If you bid on form fills, you will get form fills. Whether they are worth anything is a separate question the algorithm was never asked.
The switch
Push a sales-accepted event back into the ad platform via offline conversion import. Give it 4-6 weeks and enough volume – roughly 30 conversions a month per campaign – before judging it.
What usually happens
Raw lead count drops 20-40 percent. Cost per accepted opportunity drops further. Sales stops complaining. That trade is almost always worth making.