I hate manual startpos editing, especialy when you have to change region stuff and have to find them in the Region Array. I made a list of what is what some time ago but lost it.
To not make that mistake again and to make things easier for you I will post the Numbers of the Region Array of regions I mod here:
Western Roman Empire Provinces:
Britania Infirior: 27, 56, 92
Britania Supirior: 46, 112, 157
Belgica: 16, 64, 155
Lugdunensis: 52, 77, 113
Aquitana: 54, 62, 105
Narbonensis: 63, 133, 161
Maxima Sequanorum: 60, 130, 132
Liguria: 17, 115, 177
Raetia et Noricum: 15, 87, 164
Pannonia: 81, 148, 171
Dalmatia: 4, 108, 149
Venetia: 24, 32, 33
Italia: 41, 53, 109
Magnar Graecia: 59, 67, 119
Tripolitania: 8, 13, 23
Africa: 35, 72, 144
Mauritania: 129, 160
Insulae Occidentalis: 79, 101, 168
Baetica: 85, 123, 183
Lusitania: 69, 135, 167
Carthagenisis: 66, 99, 176
Tarraconensis: 11, 22, 30
Gallaecia: 36, 125, 126
Eastern Roman Empire Provinces:
Dardania: 37, 38, 40
Macedonia: 118, 154, 170
Thracia: 10, 136, 165
Insulae Orientalis: 19, 20, 83
Asia: 14, 122, 181
Bythinia: 34, 124, 179
Cilicia: 1, 114, 153
Cappadocia: 26, 82, 88
Syria: 5, 110, 134
Osrone: 6, 68
Palestina: 80, 162, 185
Aegytus: 120, 121, 158
Lybia: 70, 111, 117
Hope to add more and hope you may add to this list to.