Finally I found where the problem came from !
We are using a NAS Synology to share the printers drivers. It’s a share accessible without password (guest account enable on the NAS). We’ve got no access problem to this share at anytime.
This NAS is joined to the domain… And here is the problem !
As soos as we unjoined the NAS from the domain, FOG printers are pushed without problem.
I don’t know why but if you execute printui command as local system account when the drivers files are shared on a NAS member of a domain, there is an access error. If you try the same command as local Administrator, it works…
So unjoining the NAS from the domain was the solution.