After doing some research, Paradox have taken some suggestions from the forums done after the last DD, so they have been working on a rework of the starting setup for the countries mentioned in said Dev Diary.
In the newest Developer Diary, Paradox Interactive developers have given credit to a certain individual who has given incredible suggestions on their forum.
The suggestions made by the person, with the profile name ajsieg, have made their way into the game, and apparently, his suggestions are not the only ones. Paradox have, retroactively, added new stuff to the countries from the last Dev Diary, as they found them to be a fit for the game.
Now, the Mossi Kingdom has been split into 3 realms: Yatenga, Fada N'gourma, also known as Gurma, and Wagadugu. Additionally, the ahistorical state of Macina has been annexed by Mali, although, according to Paradox, they are working on a better balancing of this area, as Mali may be a bit overpowered with these extra provinces.
Also, in every Bambara province, there is now a Segu core. The event "Emergence of the Fulani" allows you now to switch your country to Fulo and the event "The Ashanti" allows you to switch your country to Ashanti. As well as that, Songhai's decision "Focus on a Professional Army" now costs 75 mil power instead of 200 per ruler and the Songhai mission tree has seen some QoL changes.
By hovering over the triggers and effects you can read what the eventual branches would request of you if you select any of the two paths that are part of these changes.
In the most recent Dev Diary, the one showcasing Ajuuraan and Ethiopia, Paradox have asked fans to give them more feedback as it may have a chance of making its way into the game itself, as part of these, reformed, countries.