Other than that I'm up to level 19 and the only other thing is that the CastelF is way slower than it should be. It's about the same as a light pinnace and slower than a light fluyt and way slower than a Polacca.
I've tried some experiments to check this.
Experiment 1: Start a new game with a CastelF. The quickest way I know to do this is to start as Edmundo or Lucia de la Vega, as they get one pre-assigned. (Milady de Winter would also work, if you want to try this yourself.) Then start again with one of the Vega twins to keep all other factors the same but this time pick a Polacca. And then again with a Light Pinnace.
Consistent with their entries in "Ships_init.c", the CastelF has better speed but poorer turn than the Polacca, and the Light Pinnace is worse than either of them on both counts.
Experiment 2: Start a game with a CastelF. Go to worldmap, look for an enemy group, save game, engage the group, repeat until it's an unescorted group of merchants. I was then planning to keep reloading and engaging until I got a group containing at least one Polacca; in fact, I got lucky, the first merchant group I tried consisted of a Polacca and a Light Fluyt. After bombarding both of them with grapeshot until they surrendered, I saved game again. My CastelF could easily catch both of them, but that's partly because the Polacca kept reducing to battle sails or no sails, and partly because they were fully loaded with cargo and I wasn't. So, after they'd surrendered, I boarded the Light Fluyt, stuffed my ship with as much cargo as possible, then abandoned the fluyt, turned to sail with the wind, raised full sail, waited for the speed to stabilise, then took a screenshot. Then I reloaded the savegame but this time swapped to the fluyt and abandoned the CastelF. Then I reloaded the savegame and swapped to the Polacca.
A CastelF can be expected to outrun a Polacca with a following wind, but a Polacca should have an advantage sailing across the wind because of its big lateen foresail. So, reload the savegame again, wait for the wind to increase so that sailing across the wind results in a decent speed, then save game again. Load the CastelF with cargo from the Polacca, turn to sail across the wind, wait for the speed to stabilise and take a screenshot; then reload the savegame, swap to the Polacca and get a screenshot of it sailing across the wind:
Sure enough, sailing across the wind, the Polacca is faster.
The CastelF, being from a game started as a Spanish character, has Spanish national modifiers including speed * 0.95. The enemy ships were French, so hade French national modifiers including speed * 1.05. Results might have been more favourable to the CastelF if all ships had been the same nationality.