If you really need it, use a word processor. If not,do you really (!) need it ?
Personally I doubt EN will open the app to accommodate this - producing a new layer of complexity with 3rd party dictionaries, algorithms and user extensions instead of simply applying what the OS does anyhow.
Nobody really (!) needs Evernote. Also, there's Evernote Web where multi-language support is afforded by any modern browser. Does it offer the same comfort as the Desktop version? No, but isn't comfort defined as something one doesn't really need?
Multi-Language Spell Checking without changing operating system language
in Evernote for Windows Requests (Versions 10.0 and above)
Posted
Nobody really (!) needs Evernote. Also, there's Evernote Web where multi-language support is afforded by any modern browser. Does it offer the same comfort as the Desktop version? No, but isn't comfort defined as something one doesn't really need?