Unfortunately, due to some young abuser who abused the translation system, YouTube has changed the rules. Under the new rules, contributed translations won’t be published to YouTube until the channel owner has manually approved them.
Hopefully, YouTube can figure out a smarter automatic publish mechanism later.
Some bigger channels won't allow it, but if they do you can add your own subtitles in whatever language you want here's how...
First, go to the bottom right of the video and click on the settings
Then press Subtitles/CC where you should see this screen
Once you are there press on the Add Subtitles/CC and you should get to a new tab where you see this