That's worked a treat, thank you very much .
Server launching and working with the admin panel using the following config.txt:
Update for the situation: I noticed a 200MB update occurred for my game client, prompting me to test again. I launched the server using the config below and can confirm it launched allowing me to connect accessing the admin panel.
I will note that this is still an issue ^. If the config isn't set up exactly as mentioned here: https://moddocs.bannerlord.com/multiplayer/hosting_server/#:~:text=Please note that if,on the Admin Panel then the game crashes right when you click on Admin Panel.
I will be attempting to get this to work using the new v1.2.7, unfortunately, there are some other issues with the server failing to launch on Linux using Wine so I will be attempting this resolution once more once that's sorted.
I managed to get this working (somewhat) I used the add_map_to_usable_maps option with the vanilla maps, this worked but then the server would fail to launch when adding custom maps, I reverted it and then the server wouldn't even launch, bringing up the "Disconnected from Custom Battle Server Manager" error.