Unless something changes, the alternative to having to rename the Guardians to the Indians
every single year for a historical game would be as follows:
1. At initial creation of your game, manually change the nickname from Guardians to Indians.
2. Make a backup of your teams.csv file (found in your ...data/stats folder)... just so you have it. You won't likely need it.
3. Replace your teams.csv file with a custom one that changes all refereces of Guardians to Indians. (Someone will undoubetedly make this simple mod; I certainly will as soon as v23 is released, unless someone else beats me to it.)
4. Make a backup of the modified teams.csv file because when OOTP updates, I believe it will overwrite this file.
5. Be aware of when OOTP updates, and when it does, repeat step 3.
That ought to do it, as far as I know... (I am not yet sure if something similar would need to be done with the ballparks.txt file that is found in the ...stats/database folder. Someone will know. If he doesn't yet, I can assure you that it won't be long until Silvam14 knows the answer
)
The same process would apply to minor leagues, regarding the affiliates of Cleveland that have been renamed from Indians to Guardians, with the file in question being MiLBTeams.csv.
(The first caveat here is that, to the best of my knowledge, 1st-year minor-leaguers import to their rookie-year minor-league teams based upon the minor league team name - that is the link, so to speak. So if you were to use a csv file that renames, say, the 1940's & 50's Bakersfield Guardians to the Indians, any players whose debut year was with those Bakersfield teams would not import to that team; I assume they'd import as free agents instead. The second caveat is that I cannot speak to this definitively. I
believe this is how works, though, assuming nothing about the minor-league import process is changing... Also, depending upon the era, this would be a larger issue with lower minor leagues, as that's where most players debut. So for me, I would probably restore the historically-accurate nicknames of the post 1950 AA and AAA teams, but would probably leave the lower minors alone. I mean, do I care that the 1950's North Platte Indians of the Nebraska State League are nick-named Indians or Guardians? I do not. YMMV
)
As for non-Cleveland-affiliated historical minors teams, my understanding is that this historical revision is not supposed to apply to those. The example would be the Spokane Indians, who are not affiliated with Cleveland and currently have no intention of changing their name (I believe they have coordinated their logos & imagery with local tribes and therefore not too many panties are in a bunch on either side.)
I don't know how the implementation of the above steps would impact logos, unis, and that sort of thing. Nor do I yet know the answer to this: