I would suggest a re-word to Mortar Shot. SOmething more along this maybe:
When this ship is given a shoot action you may double the range of one of her cannons. If you do you must roll a 5 or 6 to hit with that cannon. Remove Mortar Shot from the game after the shoot action.
This ship gains one 3S cannon that can shoot from any mast. If a 1 or a 2 is rolled when shooting, eliminate a mast from this ship and remove Ornate Cannons from the game.
Does this apply to any of the ships cannons, or just the Ornate one? I would suggest some text that specifies.
When this treasure is loaded, roll a d6. On a 1 or a 2, eliminate a random piece of cargo from this ship. On a 3 or a 4, this ship loses her next turn. On a 5 or a 6, bring in a crew worth less than 3 points to this ship, so long as she has the required cargo space. Eliminate Stowaway from the game once the effects of the roll have been applied.
I’d suggest some minor wording changes here. On a 1 or 2 eliminate one random cargo from this ship. On a 5 or 6 place any one crew with point cost of 2 or less on this ship, using standard cargo capacity rules. That crew assumes the nationality of this ship.
When this treasure is unloaded on to your home island, it is worth half the total gold points held by the player whose turn it is next.
This would be a powerful one I feel, if a little wonky. Would you round up or round down if your opponent has an odd number of gold on their home island?
When this treasure is loaded, roll a d6. On a 1-3, this ship must skip her next turn. On a 4-6, this ship must skip her next two turns. Eliminate False Sighting from the game once the effects of the roll have been applied.
Oof. This is like Mermaids. Not sure if the two turn skip should be kept.