This is what I would do...
- Get rid of all that janky plumbing work...the hot/cold lines, washing machine outlet box, multiple sets of shut-off valves.
- Install a new/clean washing machine outlet box, with working valves.
- Run new water lines in a more logical fashion...without the secondary shut-off valves, overlapping lines, protruding from the wall, ect.
- Run the lines close together as they come out of the box and to the water heater.
You can then trim out/enclose this plumbing using 1x material, finish grade plywood, ect.
This is essentially just building a 3-sided chase/box/soffit (with the existing wall being the 4th side) to cover up the plumbing and give it a finished look.
Something like this, except using wood...
https://www.youtube.com/watch?v=KsfA1_YESrQhttps://www.youtube.com/watch?v=KRvvGtjVPuIhttps://www.youtube.com/watch?v=ps--eBUfrv8