Another thing to consider with regards to Mordred building and establishing her Princedom/Kingdom is the aspects, events, and concepts she knows already that should be avoided in order to ensure the survivability of her realm.
Mordred experienced first hand the unintended consequences of how Artoria ruled Camelot, how by the end of her reign she had distanced herself from her own people due to her unbending stance on justice and other similar issues that rendered her inhuman in the eyes of her subjects. Mordred has mentioned both in this story and in her canon (Wikki) that the rebellion had been growing as a result of Artoria's inflexibility as a ruler and her belief that "to be king you can't be human nor show human emotions in order to protect the people" (more or less). As a result of this point of view some of her subjects and even her own knights turned away from her.
The entire situation with Mordred only exacerbated the problem, since a 'human' king would know that life is fleeting (a sane one anyway) and thus would understand the need of an heir or line of succession, which Artoria basically rejected with Mordred, and since Guinevere had yet to produce and heir (and later had the whole courtly love triangle with Lancelot) this undermined Artoria's position because there wasn't any guarantee of a stable continuation of government rule after her potential death. The death of Uther Pendragon had thrown the realm into discord since there was no ready heir for the throne (bar Morgan who was also rejected for 'reasons') and Artoria was basically just born. That was 15 years of discord before Artoria took the sword and 10 more years until she claimed the crown for a total of 25 years of the throne sitting empty and basically unclaimed. People will have remembered those years where the realm was in turmoil and would not be wanting to return to that level of uncertainty. Thus Mordred will likely both need to and want to cover that particular issue before to long, because it help lead to Camelot's Fall. Mordred is already ensuring that despite her glaringly OP and relatively inhuman abilities that she still looks after and cares for her men and others that fall under her command, in addition to readily expressing human emotions, rendering aid, and working to better their lives even if she can't guarantee a overall positive outcome.
In addition to her knowledge of Camelot's Rise, Fall, and it's inherent issues that she was aware of ( a inhuman king, a jealous and cruel witch of a sister, beset on all sides by enemies, a very problematic love triangle, a trolling wizard with no basic understanding of being a mortal human, a rejected child with parental issues and is militarily competent, etc.) Mordred has also experienced what its like to live in a 'somewhat' modern world, and thus can take some lessons from her time in Earth Bet to help flush out how to run and manage her kingdom (she did spend a lot of time in the library and a strong warrior is also an educated one).
- A capable bureaucracy that is functional, but not bloated and wasting time and resources.
- Modern economic theory to help maintain a strong competitive, stable, and growing economy.
- The implementation of a well maintained network of infrastructure to convey goods, people, communication, and military assets.
- Modern military strategy and logistics born from fire of war.
- Technological advances that would be feasible during the WHF time period based on available resources (printing press, copper ship hulls, water/wind powered industry, steam-based technology, etc.).
- Modern political, philosophical, and social thoughts and ideas.
There are a lot of options for her to work with in order to help develop her future realm and increase it's viability for the future based on what she may have learned or experienced on Earth Bet. However it is also true that certain advances based on our past and that of Earth Bet's just won't be feasible, practicable, or just shouldn't be considered at all in a Warhammer Universe (like overly tolerant, naïve, and gullible pacifists who want to be friends with those who worship and follow Chaos because they are "misunderstood", or full democracy where a Chaos puppet or Vampire gets elected, etc.).
Overall I like where the story is going and what I am saying is just suggestions for the future. Plus I'm partially trying to back the idea of Mordred having kids by providing some reasonable supporting information beyond just snubbing her parents. You do you sir and I look forward to more.