However, I've always thought America's theme should be different. It should be a sleeping giant, with no bonuses in the early game. Come the industrial age, however, the giant awakes.
American Exceptionalism: During a golden age, America gets a 50% bonus to production (instead of the usual 20%). Upon reaching the industrial era, America enters a free golden age. Upon choosing an ideology, America gets an additional starting tenet (so 3 instead of 2, if America is first to the ideology). +25% Tourism to civilizations with a different ideology.
I know this sounds like a lot, but try to imagine a game as America where your UA is essentially non-existent for the first half of the game. Try to compare this to a civ like Babylon, or Poland. You'd have to play exceptionally well to just keep up with the other civs all the way to the industrial era. More likely, you'll be behind in most demographic categories by that point, and your UA is what allows you to compete for the latter half of the game. The boosted golden age synergizes with America's Minuteman UU. To help America survive until the industrial age, those Minutemen can fight off invaders and generate golden age points, and if America enters a golden age, that +50% production will help it defend itself.
Also, it would make playing against an American AI interesting. You'd want to wipe them out before the industrial era, or you've got a big problem on your hands, of course those Minutemen would give you pause.
Thoughts?
No offense, but that's completely ridiculous. Like two levels above Poland ridiculous. Just to start:
Any good player can manage a permanent Golden Age for the last ~60-80 turns of the game.
Persia, a Civ often considered to be among the very best has a bonus of +1 Move for every unit and +10% Combat Strength. That alone makes them a strong Civ. The +50% bonus on GA makes them a top-tier Civ.
Now compare that to the bonus you want to give America: +50% Production (+30%) during a GA. That in alone is completely bonkers. It's nuts. You could outproduce any and every AI and just spam them with Cavalry/Landships/Tanks/Modern Armor.
What I'm saying is that the first part of your three buffs is already two notches over the top. Maybe something like +40% (+20%) would be acceptable if it was the only bonus they had. The only one.
But you want to give them a free GA upon entering Industrial (one of if not the most critical era of the game).
You want to give them an additional tenet, which in reality means upon entering Industrial era America get's the following (assuming you rushbuy Factories):
-Golden Age gold bonus
-Golden Age culture bonus
-+50% Production to Everything
-+25% Tourism modifier
-Two Freedom Tenets
-Six units of essentially Great War Infantry
If you prebuild some units you can rush an opponent with just that.
Even more insane:
-Golden Age gold
-Golden Age culture
-+50% Production
-+25% Tourism
-Buildings cost 25% less gold
-+2 Happiness from Monuments
-+25% Science output from all cities with a Factory (that means all your core cities, as you rushbuy Factories)
-All your other cities build Factories in no time whatsoever, seeing as you get +50% production towards Factories plus the +50% Production from your Golden Age
Another thing to take into account is that this is precisely the time where you have TONS of things to build, for example: Factory -> Hydro Plant -> Stock Exchange -> Hospitals -> Ideology Wonder
Those lategame buildings are key to winning the game. The sooner you get them up the stronger your lategame will be, especially the Production and Food buildings.
Imagine the America AI getting Ideology on Turn 120 or 130 (has happened to me countless times on DemiGod, is pretty much the norm on Deity) and rushing you with Great War Infantry. You're probably still using Crossbows and Muskets at that time.
As for the Ottomans, they had really high quality cannons and their infantry were very good with fire-arms before European mastered them. I'd suggest making the Ottoman UA siege related.
All siege weapons get a free volley promotion (+50% dmg vs cities) and a free indirect fire promotion. All melee ships get a free Coastal Raider 1 promotion.
Also, I'm not sure if it's within the scope of this mod to change UU's. If it is, I'd leave the janissary, but replace their mounted UU with a cannon UU - the "bombard". It could perhaps get +1 range, though that might be too powerful, especially with the UA I just mentioned. It could simply get increased ranged strength.
This on the other hand I really like.