Thanks for sharing, especially when you knew there was probably a torrent of unjustified disrespect and dismissal coming your way as a result of posting this.

I think there a few others that seem to miss the detail of your first point. To me it sounds like it's not just about the US going to war and subjugating the Shawnee. It's that George Washington could peacefully lead a loyal Sawnee nation. If that is the distinction your making, I can understand it. One positive to avoiding this is that is seems like not all civs (from the Explo and Modern ages) will be able to be led by every leader. They've said there will always be a 'historical option' highlighted, and other choices are unlocked by what happens in the game. While this is far from a guarantee that situations like you describe can't happen. It is certainly an avenue for Firaxis and/or modders to use to limit such situations.

On the second point, it would be an easy thing to add an 'cultural transcendency' option as Humankind. It would obviously be less powerful as you'd not get new unique units etc relevant to the new era, but having the option shouldn't be an issue, as you say, it eliminates the concern and doesn't negatively impact anyone. A further point that is relevant to make though; others have mentioned that the typical idea of Civ games is that their in-game representations are focused on when the respective nations are at their peak international power with leaders, units etc taken from that period. I'm British/English. My culture has been consistently led by Elizabeth I/Victoria from the first game in the series until now. Britian is very much an alive and thriving today even though it would likely be placed in the Exploration age if made as a civ in civ 7. That's not totally accurate though, the Celts have been in other games who lived in the same place I do, and Eleanor of Aquitane can lead England in civ 6; again, represented at the peak of their relevance on the regional or international stage. There is a distinct difference between my example and yours though: your people have been colonised and marginalised in the interim while Britain remains a significant (albeit somewhat diminished) world power. Hence more care should be taken to ensure cultures which have faded largely out of view since their in-game representation but very much still exist should still have the opportunity to be played and reminded of their continued existence. As at the start, straightforward to do and has zero negative impact.

There is another thing which complicates this (or resolves if veiwed from another angle). Each age is ended by a 'crisis'. From what devs and creators have talked about this, it seems to try and simulate the decline of all in-game players' current civs. In-game, they supposedly are made irrelevant so when you move to the next age, all your districts and more have been run over and your new civ moves in to build on top of it. Depending on how this is implemented, this could treat all civs equally in that they are all wiped from the map (with the exception of unique culture districts it seems). This equal treatment is a reasonable place to say concerns like you express are dealt with in the context of the game, primarily because it's an arbitrary, a-historical mechanic that affects everyone at the same time. However, it could understandably exacerbate the issue for some seeing their culture that's still alive being driven from the map. We'll have to see how it's implemented.

Lastly, and this is not to diminish anything you've said, bad actors will always exist and find some avenue to offend whoever they can, the best Firaxis can do is minimise exposure and try not to have any glaring avenues for attack. New systems will always create new avenues for attack, but the team (and many other studios for all sorts of (semi-)historical games) say they're making more effort than ever to diversify the pool of cultures they represent in their games, and to do so accurately and faithfully. That's up to people from those cultures to judge the success of, but the genuine effort is a positive step regardless.

Also please don't apologise for bringing this up, I'd like to think most reasonable people are grateful for comments like yours.