Sadly the main commemorative events only take place in Hong Kong and Taiwan(Macau is not included), but you know the consequence of going against totalitarian government right?.
And you miss the whole point of censorship. It's about making people reluctant to remembering it.
Any attempt at any kind of protest in China is slammed on very swiftly. There have been attempts in the past eg by Falun Gong supporters at Tiananmen Square, but it’s usually all over in minutes as the area is heavily monitored. There is no real independent media, they all have embedded censors, so even when there is a protest it doesn’t get covered. What protests do occur are usually over local issues and foreign media occasionally manage to piece together the story after the fact.
And you miss the whole point of censorship. It's about making people reluctant to remembering it.