Something I would like to see expanded upon would be the bandits of Sinathir as well as a map expansion. It would be really cool if they were a much bigger threat. We already have some events regarding bandits like the thugs shaking down Billy and the concubine running away from Ron. A possible event could be the bandits going to your base for money once you upgrade your hut to a wooden house. This would be way better then the two bandits hiding behind a pillar in the forest Northwest of Riverstone
A bandit cave, similarly to the kobold cave could be added as well, where you can break in and wipe out the whole place. Putting it somewhere here would be a great option. There already is a forest here so it would make sense for bandits to hide there, given the dense vegitation
Alternatively, a quest where the mayor asks the player (assuming they are part of the militia) to fight the bandits could be added. I feel like bandits are underutilized in the current version of Sinathir.
As for the map expansion, you could make it so that the crossroads area to the North of Riverstone could lead to the other settlements. 
Although making settlements like Arc and the something Graveyard are going to understandably take a long time, creating a map expansion for the road that leads to there would be great!