Interesting. The Jinma backhoe I have is a full frame mount which ties to the lower 3 point pins and the loader mount. I added a bracket that also ties to the top link mount. The reason was that the lower ladder frame had a tendency to break at the mounting slots, This one came with a beefed up lower ladder frame right from the factory.
The factory loader mounts to the bell housing and has arms going forward that connect to the battery box at the front. This transfers a lot of the load forward and onto the frame.
I have wheel weights and without any extra weight can lift the rears off the ground, but just barely. With an implement hanging off the back, the loader just isn't strong enough to do that. I think that limitation is a "saving" feature which prevents abuse.
I take extra precautions to not lift too much with forks or anything that can compound the stress put on the loader and am also extra careful about not "Ramming" into anything to load the bucket.
There are times I would like to mount a blade on the loader instead of the bucket so that I could move snow earlier. I still haven't figured out how to transfer the forces from the blade directly to the frame to keep from abusing the loader arms. They weren't made for that kind of work. Last summer I cut the brackets off the bucket and converted it to a skid steer mount so that I can easily change out attachments. So far the bucket is the only one I have...
Please post some pictures of your modification.
