Well usually the "park cable in" doesn't go to the amplifier plate. The amplifier is for OVA (over the air) signals received from the crank up or some other kind of TV antenna located on the roof. Notice I said "usually" as some rigs may be wired differently but park cable is USUALLY already amplified thus no need to run it to the amplifier. The two from my experience will never be run to the amplifier plate as you have drawn in your diagram. There is usually a separate outlet jack for the park cable vs the TV antenna.
What I have done in the past with our old rig was that I replaced the OVA TV antenna on the roof with a crank up satellite dish. Since the cable for it went to the amplifier I removed it and hooked the cable directly to the Sat. Rec. Since in our old rig the park cable in jack ran only to one spot in the TV cabinet I would (when needed if the roof mounted dish didn't have a clear shot) hook up a portable dish to the park cable in jack on the rear of the rig and connect the Sat. Rec. to that jack in the cabinet instead.
I would suspect that the two jacks on the wall with the cables going up to the roof you cant trace are outputs to other locations in the rig, perhaps a jack in a compartment or a 2nd TV location. Most RVs come equipped with a video switch box that allows you to choose from up to 3 different inputs and 3 outputs. This box would be connected to outputs like this.
Your diagram is a bit confusing and out of place with what I have seen in RVs in the past. I think you might have a few things still "confused" It would be really nice if the manufacturer would label what all the jacks do, such as Input or Output, To 2nd tv, To compartment output, etc. They just kinda leave that up to us to figure out and by the number of guys asking questions about it here I figure it is quite a wide spread problem.
Good luck, hope I didn't muddy the water and answered your question. To be honest now I can remember the question.....