If they had one more programmer like you, they would've finished porting New Horizons long time ago. Instead, we independent enthusiats have to do it for them. I have used winmerge and replaced a few scripts with the AiShip.c that your provided with your ported New Horizons and now it goes past the Loading screen and the games starts fine. I have noticed though that it skips the video that loads when starting Free Play and Sea Hawk storyline about Oxbay being attacked. So it just skips it but it works. In your current port (from 2016) it shows the video. I will have to check that as well. Also I have no success in fixing the spyglass. When you press Ctrl key in first sail mode, nothing happens. I can see that the ispyglass.c file is there in Battleinteface folder, so it's not missing.
Here's the fixed AIShip.c file (but not completely checked with WinMerge):
https://mega.nz/file/BKwg1QiT#MqvbXa9Iv0xndj79akSbT3-cF3zmaRK5UfGokz4yvFs