This is a great plugin! However ... is there an option to prevent the plugin from inserting empty keys into the other language files?
I think it would be better to not insert the key if no translations were provided, than to have it insert empty keys, simply because it's better for visibility and maintainability ...
It is currently not possible to do so. I don't want to just change it since other people are not expecting this behaviour. I suggest you post a feature request and I will consider making this a configurable option in the plugin preferences.
Starting from release 0.7.6, empty keys are no longer saved by default. This has become a configurable option.