Well, 'Guilliman: Lord of Ultramar' is also a very good one. It gives a deep look into his character, his upbringing in Ultramar, his values that were instilled in him from a young age, and how those shape his actions and decisions throughout his life.
A common theme is leadership. Guilliman is a great leader, so many fanfics explore how he leads in different situations, like during battles or when dealing with political unrest in the Imperium.
One great piece of Roboute Guilliman fanfiction is 'The Primarch's Return' which delves into his post-resurrection experiences and how he readapts to the Imperium. It really captures his essence as a leader and strategist.
I don't have the exact answer off the top of my head. It could potentially be in one of the more recent series or standalone novels, but you'd have to check the detailed plot summaries or consult with other avid fans of the Black Library.
Twin sister manhwa frequently feature plots where they face difficulties in love or career and have to support each other. Sometimes, there's a mystery or secret related to their birth or family that they need to uncover together.
In caricatures, France could be shown with its famous landmarks or cultural symbols in a humorous or exaggerated way. For Africa, common depictions might involve wildlife or traditional elements, but sometimes in a simplified or distorted manner. It really depends on the artist's perspective and the message they want to convey.