Change language

For my work I write a lot, about 50% English, 50% Dutch. I work mostly in Pages, Numbers and Keynote and try to stay away from Microsoft Office as much as possible.

I would like to be able to switch between English and Dutch for things like spelling suggestions, date formats, time formats, decimal formats etc but it is too much of a hassle to go to System Preferences>Language and Region as changing the system language requires a full reboot of my computer.

I know Word can do this, but long time compulsory exposure to Microsoft software has made me a hater. Microsoft may be your cup of tea, but for me it is not an option.

There are no differences between (UK) English and Dutch keyboard layouts, so that's not a problem.

I would prefer the names of menu items etc to not change as this messes up keyboard shortcuts, but I could probably get Keyboard Maestro to work around this.

Is there an easy and quick way to tell Pages (and Numbers and Keynote) to switch from Dutch to English and vice versa?