Good day:
The bike is a C0-Motion Tandem. It has the ultegra triple FD. It is mounted correctly and I have had no issues with the chain coming off the big or small rings. The main problem is balky shifting from the middle to the large chain ring. When I am in the large ring and the small cog, the chain rubs on the outer plate of the front derailleur. If I manually pull on the cable to increase the tension, the plate moves laterally and the chain rub is eliminated. I have an in-line barrel adjuster that does not seem to do anything.
My first question: While seated on the bike, theoretically trying to adjust the in-line barrel, which way do I turn it to Increase cable tension? CW (toward the bike frame), or CCW (away from the bike frame)?
I find it difficult to pull the cable taut. I bought a fourth-hand tool. First, I found that there was not that much excess cable to engage with the tool, and when I did, it sort have caused the strands of the cable to come apart. It crushed the cable. What I do is I shift to the small chainring and the largest cog. I loosen the pinch bolt. When the cable is off of the front derailleur, spring pulls the mechanism into the down tube. Is that supposed to happen?
Next, I'll grab the cable with a pair of needle nose pliers and pull as hard has I can and secure it to the FD with the pinch bolt.
At this point , it will usually be able to shift from the middle to the big ring, but I will still have the chain rub. I don't think it is a problem with the high limit screw because the mechanism is not at it's limit. It will still move if I pull on the cable.
Suggestions? Please?

Go to the Park tool website and read up on the subject. There are both high and low limit screws that need to be set and the barrel adjuster should be screwed in nearly all the way, before attaching the cable to the FD. The barrel adjuster has normal right-hand threads. If you turn it CCW, it will increase the cable tension. There should be no need to pull the cable extremely tight or use a fourth-hand tool.

https://www.parktool.com/blog/repair-...ur-adjustments

The FD does swing toward the down tube without the cable unattached, but in that position, there is a low limit screw that is used to adjust the cage, just far enough to the right so there is no chain rub, when you're in the largest cog. After that's adjusted, the barrel adjuster screwed in (CW) and the shifter is in the little ring position, you can attach the cable and begin applying more tension with the barrel adjuster.

I suspect your outer cable may be breaking down allowing flex, not allowing you to tension the cable properly.
Your outer limit screws seem to be adjusted "OK" and the inner sprocket adjustments are dependant upon cable tension.

If you're having trouble pulling the cable tight enough for the adjuster's range because of the extra length and poor routing or whatever, you could screw in the lower limit screw a few turns before attaching the cable. Prolly take a bit of trial and error.

That could be it, try shifting into the big ring without turning the crank to compress the housing, and see if it deforms and and takes up cable pull without moving the derailleur further.

I also notice that the Jagwire Rocket In-Line Barrel Adjuster does not seem to have any terminal stops. It seems like I can turn it in either direction infinitely. when i hold the cable, and turn the barrel, I really don't feel much happening. I will say that when i first got the bike, the adjuster did seem to affect the shifting, but not so anymore.

The adjusters do not regulate the shift wire tension, that is set by the spring in the derailleur. They change the length of the cable housing by physically changing its length and indirectly the length of the inner wire such that the position of the derailleur at a given shifter position is varied. If your front derailleur is against the low stop and the wire is slack it will have no effect. When you are on larger chainwheels you should easily see derailleur movement as you vary the adjuster position. If there is no movement the adjuster is not functioning properly.

ah, thank you that clarifies alot

That statement is really not correct. The longer the housing is made, by virture of turning the barrel adjuster, the greater the tension on the cable. If the cable is loose to start with (no tension), then turning the barrel adjuster will bring up the tension, without moving the position of the FD. The cable tension adjuster should NOT be used to move the position of the FD, at either limit - that's what limit screws are for. If the adjuster is turned too far, it will lift the lever arm off the limit screw and make the limit screw useless. With Campy triple FD's you want as much tension as possible, without lifting the lever arm off the limit screw. Many users fail to do this and have to use a double sweep of the finger lever to make the shift from the little ring to the middle. If adjusted properly, that is not required. Some users ride for years without figuring this out - they're using extra finger lever clicks to make up for inadequate cable tension.