Ironclad keyword looks okay, combining two existing abilities into one is cool. I would advise using language similar to or exactly used by WizKids. In this case the second half of the ability would read thusly: Ramming cannot eliminate this ships masts.
Return Fire would need some re-wording I think. Possibly something along this line:
“When this ship is shot at, after the attacking ship has fired all of their cannons, as a free action this ship may be given a shoot action to shoot with all of her remaining masts. For this shoot action this ships cannons increase to rank 4.”
It could probably be better said but the above specifies when and how the ship returns fire.
For the treasures, both should have language that specifies when they are used or go into effect. For example: when revealed, when given a move action, when given a shoot action, etc.
For ships and crew with multiple distinct abilites, I recommend seperating those abilities with periods instead of commas. That small quibble aside I like Johnson. I think his second ability should be more clearly stated, such as: this ship gets +1 to all d6 rolls. Additionally his final ability should specify is the repair action is a free action or not. Given that a bonus to all dice rolls is VERY powerful, Johnson should probably increase in point cost, from 6 to closer to 10 or above even.
Emile is quite similar in that regard, should probably cost more than 7 points, though I do like his combination of abilities.
Le Ronde seems like an interesting ship, though her 2 cargo spaces will limit what she can do significantly. Is her last ability meant to be exactly the same as the Glorious Treasure’s or is it meant to be different slightly?
Unless you’ve got a different model in mind, the Pinnacle should only have 3 cannons/masts as Turbine’s were never larger or smaller than 3 masts. That said a few people have made 4 mast Turbine ships so it’s not out of the realm of possibility, just something to keep in mind if you ever manage to bring the ships off the paper.
All of the events should have a range specification, measured either from the token when it’s placed, or from some other point that is specified in the ability. For example: Every ship within L of the event token must roll a d6 before being given a move action; Every ship withing L of the chosen island/terrain must roll a d6 before being given a move action.
Additionally, what would the point costs of those Events be?
Wind in a Bottle needs more concise wording, like the other two Unique Treasures.