Thank you for contacting us.
Currently we don’t have a overview of articles and a quick edit function to add keywords to them. But what we have an export and import function available where you can edit your keywords.
This is export option: https://prnt.sc/oArjFH4JJ13Y
In the CSV editor you should see something like this : https://prnt.sc/0hgVzRnjs3tb this should list all your posts/pages etc you can edit your file directly before importing it back again. You can add multiple keywords by separating them with commas.
Some users encounter issues with file imports because of file formatting issues, this might be caused by the editors used like Excel. I personally used Modern CSV to edit my CSV export, there is a free version of this and there is also still another software editor there for CSV that can help you properly output CSV formatting.
For imports that have no new items or keywords other than the already existing ones saved, the import will return the message Nothing to import. If this is the case the import does not fail but rather found nothing new to import.
I hope you understand.
Please feel free to contact us if you need more help.
Thank you