I can not change language to Chinese on Linux.

Are you still having this problem? Because I'm having the opposite!
I'm on a Linux box and am trying to download a Windows version in English, but it seems my only option is Chinese! I'm in America, FWIW. No problems with any other of my many GoG games.

Nevermind, I guess I don't have a real problem after all.

The language selected at the top of the page is Language: English, the download URL has "en" in it (https://www.gog.com/downloads/iconoclasts/en1installer0). but despite that, the file downloaded is "setup_iconoclasts_1.15_-_chinese_(24911).exe"

But I guess that isn't a problem. The installer was in English and when the game started I got to pick English and all's well. Nothing about this seems like Chinese other than the filename of the installer. Weird.

I wonder if some bits of content will be censored or uncensored or in a different color or something.

I think it's just that the most recent patch was called "Chinese", since it added Chinese language support to the game.