I've never used Attila AK before, and had previously thought it was the same of Rome 2's counterpart. But Attila's AK seems much more complicated as I messed with it for two whole days and it didn't produce anything of note. The AK (BOB, specifically) would either A) crash the Attila loading screen (two consecutive "Attila stopped working" windows error info prompts) when BOB is processing the startpos, or B) freeze the Attila loading screen (as windows task manager couldn't end the process, I only have to resort to a restart), or C) luckily succeed in producing pack files, but using which in Attila mod manager with no other mods enabled would again cause Attila to crash on loading screen (one "Attila stopped working" windows error info prompts).
I'm pretty sure I've done most of the stuff right, as I've done a small overhaul on Rome 2 actually.

For instance, as a small exercise, I'd like to unlock vanilla AFRICA faction for a potential Gildo rebellion campaign mod.
Firstly, 1)I would give several settlements (regions) in
Code:
start_pos_regions
in table launcher from WRE to Africa, which was landless at the start. To ensure this, 2)I have to check either in
Code:
start_pos_character_to_settlement
tables (Table Launcher) or in
Code:
start_positions
(Form Launcher) if WRE has anyone left in the aforementioned settlements. (In my case, only Constantina has dependencies belonging to WRE in Province Africa and Province Tripolitania) And furthermore, 3)I should assign at least my custom faction leader (Gildo) onto the map as the Africa faction is an empty faction by default. This process would go smoothly in Rome 2 as it demonstrated by so many tutorials on this site. But even this single step would cause one of the three crashes listed above.

Alternatively, I could theoretically unlock the Africa faction by creating two political parties (ruler and council ones and their percentage) in
Code:
political_party
tables and allocating them to this faction in
Code:
faction_political_parties_junction
tables, subsequently, I would tick the Africa faction to be playable and deal with all relevant stuff in
Code:
 start_pos_factions
table and check its cultural properties (whether it's compatible with WRE buildings) in
Code:
factions
table. Finally, I would apply the ruling party to the custom faction leader (Gildo). Doing these, BOB would function normally, but the produced mod would crash the game instead, before even entering the main menu.

Idk whether setting up
Code:
frontend_leaders
would help, but it actually still crashes when I clone values from corresponding unit blocks in that table. I don't do much around faction leader model stuff though because it's new in Attila and there's hardly any tutorials regarding this on TWC, as nearly every tutorial would say that "Attila system is the same as Rome 2's.

Idk what I had actually missed in the steps above, and I'm very much in need of your help, Thx!

Additionally, I want to mention several differences in startpos modding between R2TW andATW, first being Attila would ask users for permission to launch, rather than launching itself as does Rome 2, and failing to check Steam would result in "Failed to locate TW launcher"-alike error infos. And there are several threads indicating that it's crucial that we should refuse ATW's launching request and instead manually launches ATW by clicking Play buttom in Steam library, as is demonstrated in Magnar's youtube tutorials last year. I just don't know whether the refusing action is still needed, and I don't notice any difference, as either method couldn't save my game lol.
The second difference being the exporting and packing procedure, as either the campaign startpos.esf in working_data is selected in Dresden's, Caligula's and Magnar's tutorials, while precise itms in raw_data are selected and packed, demonstrated by Miguel 80 when he showed us how to enable the Duchy of Croatia in AoC last year. All of which are just more complicated and confusing than in Rome 2's case.
The third being system differences, as the horde system as well as the faction leader system would probably make things complicated when dealing with land switching (because migrating hordes have their own buildings and would not be straightly assigned to new settlements) and faction unlocking (the frontend character stuff),

Anyone who has done Attila startpos successfully editing would be more than welcome to explain to us the right way to do startpos in Attila. Thousand Thanks Really!!!