OpenDevEd has been streamling our Google Docs / Sheets / Slides workflows for many years, going back almost until the initial launch of apps script. For more details about all our Add-ons, see Our Tools.
BUtils for Docs provides a number of utility functions for Google Docs. In particular, it provides functions related to tables (including extracting text from tables to form paragraphs, as well as turning paragraphs into tables), some regexp-based functions (e.g., for text formatting), as well as facilities for marking words in UK vs. US spelling.
For details, visit our GitHub repository here google-apps-script/repositories and select BUtils for Docs.