Yosemite changes QWERTY keyboard layout

I'm also a kotoeri user, and it took me a while to understand what's wrong.
In fact, the former behavior (e.g. option-e, then e = é) is not available anymore
in kotoeri alphabetic (symbol A in the task bar). However, it's still available in the
US input (symbol american flag in the task bar).

What I wanted to do:
- Switch between european languages and japanese with command space;
- Get the former behaviour when in european mode.
What I did:
- Open the preferences, go to input sources;
- Remove everything except U.S and Japanese hiragana;
Then it works again. The only difference is that it used to be either
alphabet (letter A) and now it's the US input (American flag). And in
american mode, you can use all the former option + key combinations.

That's it!

Pascal

As far as I know, Yosemite Romaji IM's failure to honor option and shift dead keys is a bug that Apple will have to fix via an OS update. It has been reported elsewhere (e.g. https://discussions.apple.com/message/26864874#26864874 ). It would be good to use Apple's feedback channel to encourage quick action on this.

The OS X 10.10.1 update does not fix this bug in Kotoeri, but the 10.10.2 update of Jan 27, 2015 DOES fix it.

The behavior described for the US International PC keyboard layout is not a bug, but intended. People who use this keyboard want the ` ~ ^ " ' keys to be dead keys for producing accented characters, and they learn to add a space when they need the stand alone version.

I have not seen any other reports of the US keyboard layout not working right in Yosemite. When the US flag is showing at the top right of the screen, you should be able to use the standard option dead keys to produce accented characters without problems. You should also be able to use the Character Picker, where you hold down the key for the base letter and a popup menu appears where you can select accented versions. If that is not the case for you, the OS is broken somewhere and may need to be reinstalled.

I also upgraded to Yosemite (from Mavericks) on a MacBook Pro with a US Qwerty keyboard. But I do not see any difference in behavior with the keyboard, i.e. all the combinations you indicate (option+e to get "é", ...) still work fine for me. I did not make any change during the upgrade.

My keyboard is set to plain "US" (not "US Extended" or "US International -PC").

I only type in English and French, so I don't need any additional combinations.