Sorry no data, but unless there's something to reliably capture the fragments/projectile then they are going to strike something in a 360 degree area around the impact. I like this video to show new instructors about the safety considerations when setting up a steel range sessions.
But let's be clear, the fragments that come off a plate even without ricochet are moderately unpleasant. They eat away at concrete and metal over time. Softer materials (fabrics, chipboard) handle them better I guess because they are fast but very lightweight, but I wouldn't want my head in the way.
I have heard many, many anecdotal stories, and over the years seen a handful of autoposy diagrams and AAR photos of serious ricochets from steel rifle and trauma plates. But I cannot find much online, and anything definitive or scientific about it.
Weird. And disappointing. I have been having arguments the past two weeks at work about something nerd security related and am winning because I can pull out stuff like new NIST standards. I was likewise hoping that things like NIJ 0101.06 would cover this, but they seem to not consider the actual context of use. In fact they explicitly consider a deflection a "stop," with no consideration of where the deflected projectile goes subsequently. Of the other standards I can find, none of them are more illuminating.