Yes. You can replace the cables without replacing the valves. I purchased, cut to length, and replaced the grey tank cable on my 2016 Solera 24W. I was able to just shorten and reroute the black tank cable. Both cables now have almost a straight shot with very little bend in them and they work just fine. I did not have to replace the valves. Now, they are easy to operate, and do not leak. All is well. I contacted Brian Clemens about them when I was having the problem, but didn't push it. I did not ask for reimbursement since I was able to do the work myself and the cable was not expensive. I used a Valterra cable for the grey valve.
FR could easily cut those cables to the proper length before installing them at the factory. It would take a few minutes per cable but would be easy to do on the bench -- much easier than after the valves are installed.
How to do it:
There is a bracket/protective cover where the cable meets the valve. On the black valve, you have to loosen the bolts that hold the valve in place in order to pry the tabs that hold that cover in place away from the valve. The one on the grey tank valve is smaller and is held in place with a retaining clip that has locking tabs on two corners. Release the locking tabs and open the clip, then just remove it. There is a screw on the brackets where the cables meet the valves. It holds the cable retaining block in the bracket. Remove the screw and slide the bracket back away from the valve. You will have to remove that screw before you try to separate the bracket from the valve or it will prevent it from moving away from the valve.
There are two set screws that attach the cables to the valves. There is a set screw that holds the cable in the small retaining block where the screw was. That one goes in from the end and secures the cable in the retaining block. The other one attaches the cable to the rod of the valve. Remove both set screws to separate the cable from the retaining block and the valve rod. You may need to pull a bit to get the cable out of the valve rod after removing that set screw because the set screw bends the cable end a little and that actually helps secure it to the rod.
You will have to cut away some of the foam that is sprayed on the underside where the cable handles are mounted. Cut away as much as necessary to remove the nut that holds the cable to the access cabinet. Remove the nut and pull the cable out.
I recommend rerouting the cables to minimize the bends, then cutting them to fit. Here is a Valterra video that provides some helpful insights for replacing valves and cables. It talks about cutting and routing the cables starting at 7:15 into the video.