From the German locations included in this huge nomination, I have seen only remainings of CASTRA REGINA in Regensburg (already WHS by itself) as several parts of its fortification are still visible "in situ" (I have seen maybe two- or three-times during my occasional visits of Regensburg). The best known and at the same time the most spectacular part is PORTA PREATORIA (PHOTO), which is quite nice and impressive structure takeing into account how old this gate is. I had also oportunity to see the excavations below Niedermunster church located quite close to the gate, and parts of walls of late Roman barracks or residential villa are presented for organized tours in the underground of the church, but these are not very spectacular.
My opinion is that it does not deserve WHC status at all. Regensburg is already WHS and better preserved PORTA NIGRA in Trier has been already inscribed as well. Despite my skepticism towards this TWHS, I expect smooth after-referral inscription in 2020.