Don’t know where to post this trick but it made my day ! If you’re using the WOPI app and a office online server when you create a new .docx file and the UI is in your local language but not the dictionnary (or spellcheck language) here’s how to fix it :
Create a docxtemplate.docx file on your computer with the right language
Then ssh into your nextcloud server and do the following
chmod 775 /your_path/apps/wopi/assets/*
copy your file over ssh or ftp in the /your_path/apps/wopi/assets/ folder
chmod 644 /your_path/apps/wopi/assets/*
I’ve been banging my head for quite a long time over this