SlackBuildsOrg/office/diction

diction (grammar checker)

GNU diction and style are free implementations of old standard
UNIX commands, that are not available on many modern systems,
because they have been unbundled. Diction prints wordy and commonly
misused phrases. Style analyses surface characteristics of a document,
e.g. sentence length and various readability measures, but unlike the
original code, it lacks sentence type, word usage and most sentence
beginning processing.

Both commands support Dutch, English and German documents.