[Divingduck]

In addition to what BetterRed already said, there are only some workarounds possible.

You can only use more than one normal dictionaries if you tell calibre that a special word, a paragraph, a html file in a document is in a particular language that differs from the main language. As BetterRed already pointed, doing the stuff word wise will be a horrifying job.

So, if you need to do this, do it outside and import your work again in the editor.

An other workaround is to use more than one user defined dictionary. That's what I do if I had more than one language involved. To generate a specific additional language dictionary I change the main language definition from e.g. English (main, 1st) to Spanish (additional, 2nd) and copy all accurate words in an additional user dictionary via clipboard. If not already done, create in the editor a new user dictionary and paste your word listing via import dialog into the new user dictionary. Don't forget to assign as import language your main language (English) for your non english words.