...until selected to take a carriage-ride, where 2 of my party was left-behind in Umar Hills.

Re-loaded the auto-save, but this seemed that was taken after the bandit-cut-scene, but this seems to have been taken a little bit too soon, since wasn't possible to get-back status-messages and player-portraits and so on, except by going into inventory or similar.
Re-loaded again, didn't take carriage-ride, and landed by river...
When this was finished and wanted to continue, Sime triggered the dragon so again left me without any status-messages and so on...
Since atleast one of the problems was due to Sime, it's possible none of these problems was due to SoS but TS instead...
But anyway, landed in Soubar, and 1st quest went without any problems. Trying to start 2nd quest on the other hand doesn't work...
... since ar4232.tiz isn't being de-tizzed by sos-tisoggbiff.bat and is therefore not installed as it should...