The Yanmar loaders that were sold by Yanmar for US models were made by by American companies as were all the other attachments that they marketed here.
My US Yanmar has a Great Bend loader with full subframe. (I think it was first sold with the loader installed since it has the HD front axle option.)
This Great Bend subframe looks similar to yours but the arms to the rear are not quite as heavy. It also has tabs to carry some stress forward of the bellhousing to the front axle's chassis. This seems to work. The bucket has dents showing it was used to ram things many times, without hurting the tractor.