Anyone is using helm-bibtex to manage papers? Is there any way to create an extra column indicating reading status (done, reading, etc.)

yep, you can put this status into your own bibtex field (lets say "mystatus") and then customize the `bibtex-completion-display-formats` variable to include "${mystatus:width}".

Thanks! I’ll give it a try

also check `bibtex-completion-additional-search-fields`