Someone told me to plead my case here

DISCLAIMER: Haven't read the whole thread.
I often edit ebooks which feature many foreign words, whose (the words') language is not marked in the code (mostly because said ebooks come from OCR, and also because those words are scattered throughout the book in a very unorderly fashion). I would really
love to be able to spellcheck against the
sum of varying numbers of dictionaries (i.e. having the spellcheck only list the words that are not present in
any of those dictionaries.
As things stand now, when correcting a long book (typically university textbooks on humanistic subjects), I find myself scrolling through a list of thousands of words, many of which are in some language other than the one the text is actually written in, and 99% of which are false positives.