Code review comment for lp://staging/~cosmos-door/ubuntu-keyboard/japanese-keyboard-rebooted

Unfortunately I found an extra issue, one of the changes made to the core breaks both the email detection and mid-word insertion based disabling of pre-edit for all the other plugins.

const bool enablePreeditAtInsertion = d->word_engine->languageFeature()->wordEngineAvailable();

^ wordEngineAvailable isn't really an appropriate feature to check for this, as that's going to be true for pretty much all plugins. I think you really need to explicitly add a new language feature for this (which could be called enablePreeditAtInsertion), that's true for Japanese but false for all other plugins.