[kovidgoyal]

@Divingduck: Attach a file where you cannot jump to the next occurrence.

As for importing wordlists as user dictionaries, I can certainly implement that. However, in calibre a user dictionary contains not just a list of words but every word also has an associated language. Therefore, they cannot be exported as simple word lists without losing some information.

I dont understand why you need to turn off dictionaries. The spell check is perfectly capable of handling multilingual documents based on the language specified in the lang HTML attribute.