They are calling out on leads we send them, then conducting a warm transfer if successful - as they make calls on them, they are sending status and activity updates, hence the turnaround time.
Actually got everything squared away - my contact on their end had the right URL all along as he's had a bit of experience working with posting info to Marketo, but did not have the proper command or filter to "updateLead" correctly, but we literally got everything corrected and squared away about 11 minutes ago. Things are humming along nicely now.
It's been quite the learning experience, and I truly appreciate the help and patience of the community.