Firstly, before I start with my list, I do want to clearly state that I do support more representation in board games. I especially think that there should be more representation in Euro games. Euro games tend to, there are exceptions, but they tend to have a fairly pasted on theme. I would encourage them pick themes that allow for broader representation. And, the fact that, by and large, they are not doing so is something that I believe needs to be changed.
With that disclaimer out of the way..... If you are going to design a historically themed euro, don't whitewash the problems. I am fine with games about colonization themes in euros. But don't give me cards that are called "native." At the least, do enough research so that you know what the names of the native peoples were. If my prospering is caused by slavery, well, then tell me so, explicitly, in the game. A famous game often acused of whitewashing is the great game of #Puerto Rico. In that game you use brown discs, called colonists, to work your plantations etc..... The acusation is that these discs are brown, because the discs aren't colonists, but slaves who you are buying to work your plantations. There are many people who have a problem with that percieved whitewashing. I don't know if that is whitewashing or not. The fact is that, while there were some slaves in colonial Puerto Rico, for the first several hundred years of its colonial history the economy was primarily colonist driven. So, maybe that isn't a case of whitewashing.
I really don't appreciate when there is obviously no thought about the historicity of the culture wherein the game is set. A hilariously bad example of this is #Manitoba. This is a game supposedly focused on the cree people. But, the have totem poles fairly tightly integrated in the game. Of course the the Cree, to our knowledge, never made totem poles. Those were almost exclusively, if not exclusively, a product of the first nations groups in the NW west of North America. It also has this bit of flavour text. "The Canadian province of Manitoba is wild, fascinating, and almost without any limits: countless lakes, majestic mountains, a vast tundra in the north and endless prairies in the south." Manitoba, Majestic mountains???? Their highest point is Mt. Baldy at 2730 ft above sea level. I mean Kansas has their highest point at over 4000 ft above sea level. I wish this were a singular example, but, unfortunately it isn't. There are lots and lots of examples of this sort of hanky panky laziness. So, please, if you are designing a historical Euro, do at least a little research.
I really deplore the paucity of themes in historical euros. Do I always have to a merchant, or a noble, or colonial governor???? really??? Do I have to always be stuck in "trading in the mediterranean?" do I have to be colonising? or banking? If you are designing a game in which the player has to make certain quotas by the end of the game, or round or whatever, why don't you cast the players as slaves on a cotton plantation in the south? If you are desinging a punishing game, and you want a historical them, why don't you give me a game where I am representing a native American, or native African group pushing back against western expansion? There are scores of ways in which you can do this sort of thing.
Again, this is specifically about historically themed Euro's. I do applaude the nonhistorical Euros which are coming out with new and interesting themes. But, I love historical themes. I do just wish there was more variety and more honesty in the themes which they tackle. And, if you want more representation in your game, find a theme in which you can have that representation. Don't pick your theme and then try to force history.