How about:
From what I understand of the article, Lebensraum essentially meant "Eastern Europe rightfully belongs to the Germans". This came in two parts, 1. Conquering Eastern Europe 2. Depopulating the conquered territories of Slavs and Jews to make way for German "immigrants".
If we apply the idea more generally, and in civ terms, this would mean bonuses after acquiring land (which we have), and what else? Our closest version of #2 would be razing the city to make way for one of your cities. Something like:
Hey, thanks for engaging with this. And this certainly goes out to the whole community/the people in this thread, not only to you. Also, I certainly don't want to derail this thread. I just saw the opportunity to adress people that are actually very familiar with the tenet and maybe its historical background. If preferred, I can certainly move this elsewhere.
You are correct. There was a meaning of the term in Germany before WW2, which was comparable to any imperialistic idiology, i.e. let's conquer some land for it's natural resources, riches etc. and during/after WW2 where it became a specific Nazi idiology. The former certainly included the killing and subjugation of the native population as one has seen during all ages of humanity. The latter included the special Nazi brand of race theory and the planning and execution of the extermination of millions of people in the occupied countries. One could certainly argue that there's an older Lebensraum definition which is what is referred to here, but the same is true for the meaning of the swastika symbol, the meaning/connotion of the word Führer (German for leader, but now it mostly refers to or invokes Hitler) etc. The meaning of words can change
Please don't get me wrong, I'm not complaining about the historically correct gameplay mechanisms of this tenet, i.e. if it grants the right bonuses or whatever. I think we should rename it because it is in bad taste to use this specific term because of the connotation/implied meaning it carries (btw. it's a Vox Populi name/concept, it's not included in the base game). It's a special brand of evil that shouldn't be used as a the name for a game play mechanic that "...is so cool and fun we couldn't bare to part with it." If it was just called Imperialism (I know, that term already exists) I would be okay with it, because it is a general concept. Lebensraum is a very specific thing that is connected to some of the worst atrocities every committed. The same reasoning that was applied when it was decided to remove slavery mechanics from CIV5 or not include a "Napalm bombing" promotion that grants +25% damage vs. Infantry should be applied here (and the list of things that do exist but maybe should not be included of course goes on).
CIV is a game that allows for some sort of an alternate history simulation because its concepts are grounded in human history. However, it is not intended to allow for a complete replica of human history. The game devs made deliberate decisions to omit/obfuscate certain aspects of human history that were so terrible, they should not be used as a mere game play mechanic. I think we should follow this example here and find a different name for this tenet.