Generally speaking the Germanics didn't have cities in the traditional sense, but I will see if I can find anything of interest for you.
Ostrogoth (Greuthungi) Territory: Chersonnesos (essentially where Sevastopol is), Panticapaeum (On the eastern peninsula of Crimea, north side of it), and Tanais (on the north side of the Sea of Azov). These were cities within the territory that the Ostrogoths eventually held in their kingdom.
Visigoth (Tervingi) Territory: Possibly Tyras and Olbia were Visigothic cities. They predate the arrival of the Visigoths, but they fall in its territory. These are on the mouthes of the Dneister and Dneiper respectively.
Interesting bit I just found, apparently according to the Hervarar Saga, Arheimar (said to be the capital of the Goths, though not certain if it just means the Visigoths) was located on the Dneiper. Most likely this would be Olbia, but it isn't certain.
Alemanni/Juthungi: For the most part seem located between Mainz and Augsburg at this time, but possessing neither (both were in Roman hands). Thus far I have not found the name of any cities that they held in the period of this mod. Juthungi were probably the descendants of the Semnones, a very prominent Suebic tribe from earlier times. Most likely the held land east of the Alemanni, in present-day Bavaria. Once again, no known settlements yet.
Quadi: Are closely linked to the Marcomanni, but the lesser of the two. Both have been severely reduced after the Marcomanni wars about 80 years prior to this mod. I wouldn't recommend them being in the game really. There are also no settlements named. No idea why that map has them labeled so prominently (though honestly it looks questionable, as the Alemanni also never held such a large swath of land either, unless it includes the Juthungi. Its over-simplified).
Vandals: In the barbarian hinterlands. No mentioned settlements yet. Still looking.
Franks: Less than a decade after this mod's setting, Utrecht was abandoned by the Romans. It is possible (perhaps even likely) that the nearby Franks settled in it afterward. Unfortunately sources on Utrecht in this period are few if any. The only other city of note around their lands was firmly in Roman territory (Bonn), and remained so for some time. It was a strong seat of their power in their area, apparently a nearby fort having an entire Legion.