Sorry I forgot to give you some help:
1. The nation you call Balaton was indeed a slavic principality freshly broken from Frankish overlordship. In the years of the scenario the country was ruled by a chief named Salan.
2. There is an official list of Magyar rulers. The Magyar chronicles and legends usually mention the Slavic and Bolgarian rulers of Pannonia. Here's some: Simeon (Tzar of the Bolgars, muslim or orthodox, capitol: Preslavl), Salan (both of Frankish and Slavic origins, catholic or pagan, capital: somewhere near the lake Balaton+the left one of the two provinces, not the one you chose as capital), Sviatopolk (moravian, perhaps from the Przemysl-dynasty, capitol: near Vindobona).
3. City name, culture, and owner changes (first phase): Tsaritsyn->Sarkel; Belgorod->Peyeraslavl (russian); Kiev (under the control of Halic or the Magyars); Bakhchisaray->Khersonessos (greek); Kaffa->Theodosia; Azov->Tana (orthodox); Kastamonu->Sinope (greek); Erzurum->Theodosiopolis (greek/armenian); Konya->Ikonion (greek); Antalya->Attalea (greek); Izmir->Smyrna (greek); Balikesir->Abydos (recommended); Bursa->Kyzikos (port city); Edirne->Adrianopolis; Durazzo->Dyrrachion; Nis->Naissos (still greek); Eger->Agria (latin name); Buda->Aquincum (still in use); Sarajevo->Jajce (under Croatian control!); Filippopel-> Preslavl (original Bolgar capital, Byzantine occupation); Varna->Mesembria (nearby greater greek city); Lwow->Halic/Galich (russian); Astrakhan->Itil/Ithil (original name); Lake Aral &Amu-Daria River->Oxos (these given the names of both Oxania and Transoxania(=Trans-amu-Daria)); Beograd->Singidunum (it's still used in that era)
4. Serbia is still vassal of Byzantium, Zeta is greek, orthodox, thus controlled by Byzantium.
5. I'd love a rebellious Vandal state in the Atlas Mountain (orthodox or pagan) to oppose the arabs. I think the word "berber" isn't arabic, numidian nor black-african people's name, but of the Vandals' (=Barbars') (given the name of the Barbary Coast too).
6. Alexandria would be better as greek culture and orthodoxhy.
7. I forgot to check Sicily and italy, so: the cities of Messina and Syracusae must be greek, as well as Naples (Neapolis), Taranto (Tarenton), and Bari.
8. The first settlement near Sucheava was Hungarian, and it was named Jaszvasar (estabilished before the Mongol Invasion, today Iasi). You better use this name, and you should change all Romanian to Hungarian (Magyar)
9. Recommended randomleaders for Magyars (do not use Wlach names anymore, please!), many are turkish names too: Kushid, Tasch (Tas), Titin, Itil, Arpad, Tacsony, Tarkacu, Diarmat (Gyarmat), Medier (Megyer), Jelegh, Kuert (Kürt), Jenoe (Jenö), Sol, Truntai, Almosch (Almos), Ond, Kond, Houba (Huba), Tormacu, Vaik, Kupan.
10. Anatolia (Asia Minor) was the core of the Byzantines' economy in those years. You better raise their productivity to high levels, thus renaming the cities to their greek forms, culture, and religion! Do not forget the non-byzantine controlled greek cities. Nuyssaybin (in EU2, it's Mosul, but that's Ninive)->Nisibis, and there must be greek Palmyra, Damascus, Accon, Tripolis (both of 'em), Cyrene (or Berenice<=Benghazi).
o
