Hi Auke, nice to meet you again
Unfortunately, I think that none of the above mentioned people are the same as we are looking for.
Both the 377. ID (Lechner) and the 82. ID
(Bäntsch) were deployed with the XIII. AK to the north of the city. These units fought and suffered these casualties against the upper pincer of the encircling Soviet forces (38., 13. Armies). The fighting for Voronezh occured in the sector of the VII. AK (against the 60. Army).
The G.R. 199 was part of the Gruppe Siebert (Div Stab 57) during the course of this battle and had suffered heavily while encircled at Sinje Lipiagy, to the southwest of the city. Suppose Schmidt was killed in this fighting, too, at least the date suggests so.
So these were good tries but close misses, all of them unfortunately. I'm clueless about the true identity of the man we're looking for, if there is any.