You should block off or remove the pathways that lead into the fort as guest are getting lost there. Then build a bunch of food stalls, drink stalls and bathrooms throughout the park because the people are hungry. Build some information kiosks as well (if available).
Rather than landscaping the fort, it can be used for a tracked ride. Adding tunnels, building near the existing scenery and the moat will boost the excitement rating.
The pathway near the dueling coasters is actually quite long, so you should consider building some rides or stalls around that area or the guests will be bored.
The dualing coasters are prone to stall and crash (which will certainly happen before you complete the scenario), and frequently break down as well. You should better choose to rebuild them using another type of roller coaster (those allowing longer sets of trains are better) or completely remove them and build other safe coasters at the region.
At some time you may also want to set research priorities to thrill rides as there are not much available.