The 3rd Spanish UHV is troubling to me, as it can depend too much on random chance - I did well enough to prevent Printing Press from being discovered until the Dutch spawn and had to reload several turns prior due to failures for various reasons:
First time off, I attacked the Dutch stack at spawn - they have very few troops, easy to kill. In 1586, I'd bought my vassal Germany's loyalty to the One Holy Catholic and Apostolic Church. Hungary converted to Protestantism during this turn as well. As soon as I hit space bar, Hungary converted back, but the Dutch resistance continued and a few of my Knights of St. John's appeared outside Nevers - I destroyed them again, and at this point in 1588, there were now no Protestant nations. I hit the space bar again, and Poland became Protestant, and my UHV indicator greyed out at 2/3. Either the Dutch respawn at the beginning of the turn or the Polish conversion at the end cocked the UHV up, even though I had ensured no Protestant nations by the end of my go.
All along, I had been building troops for an amphibious invasion of England. In 1588, Protestantism had not reached them - it had reached the Norse, though, but my ships were one turn out of range to win in time, though. Another restart with ships in position to reach either England or Danmark in time, and neither convert to Protestantism. :angry:
The final time, I let the Dutch settle Amsterdam, and agreed to the flip. My vassal Burgundy, however, dragged me into war over the flip of Nevers (which is fine, as the Dutch must fall). I plowed through their 3 cities and won the UHV a turn or two early (should the UHV goal be changed to conquer BY 1588 rather than conquer IN 1588 - conquer "in" 1588 implies you must capture 3 cities on that turn).
Too much chance is involved that Protestantism will reach a nation you must attack in time, and while the Dutch can always be counted on to fall easily, you also have to rely on the chance they'll have 3 cities for you to take from them (luckily my vassal settled Nevers a few turns prior to their spawn - had British Caen's culture been stronger, this wouldn't have happened).
A true "Spanish Armada" UHV seems like it would take the vanilla RFC UHV goals from the Vikings (sink X number of ships, kills by Privateers & victories over barbs don't count) or Chinese (build X number of ships). I've learned with my Privateer stacks that the AI enjoys shipbuilding, so engaging in naval warfare with England, Norse or Ottomans is certainly achievable.