The Yunohost project uses your Vagrant boxes as a base to build up development boxes (see
https://github.com/YunoHost/Vagrantfile repo). I submitted a patch to add 32bit support to their environment, as I have an oldish 32bit laptop and thus cannot run 64bit boxes. For now I built the 32bit boxes from the Bento image because I didn't find an official 32 bit Debian. I was wondering why there were not such images, so I sent you an email. As it looked to me very straightforward to adapt the json to 32bit, I attached it with my first email in case it was of interest.
I understand perfectly this issue and it answers all my interrogations.
As I said in the 1st paragraph, for the moment I don't have any particularly urging need to have an official 32bit image, I think it will be fine with the Bento image.
Thank you very much for your answer and for having brought up the existing images !