I would suggest filing or grinding the cable ends flat, like in the link I provided. This way the inner and outer housing as well as the wires will share the load and reduce the likelihood of them bending the ferrule. Of course matching the sizes will help also.
I have no idea why the left-hand housing is getting bent/kinked like that. Is your FD high limit set too tight, causing you to force a shift against the stop?
Or is the inside wire routed incorrectly around the clamp bolt? On most Shimano FDs it goes over the little tab before going under the clamp. If this is incorrect the indexing will be wrong and the shift effort unduly high.