You are on the right track with this tonearm resonance issue. It is very much a result of the amount of energy a cart is allowed to impart back into the arm. This is not only a function of the compliance, but also the damping of the cartridge itself. Some cartridges are notorious for transferring relatively significant amounts of energy into the arm.
I'm not understanding the distinction that you are making between "compliance" and "damping". In fact, I'm not sure that I understand how you are modeling the system. I will tell you how I conceive the system model and then you can comment on where I might be incorrect or leaving out relevant information.
The cantilever is attached to suspension within the body of the cartridge. That suspension can effectively be modeled as a spring. The total of the effective mass of the tonearm and the mass of the cartridge can be modeled as a mass that is attached to the spring. In a spring system, energy can get trapped within the spring when you excite the spring at a resonant frequency for the spring. That's what causes the spring to vibrate out of control. In the cartridge context, the excitation for the spring comes by way of the stylus. The source of the excitation is any energy source that couples through the stylus, this includes the groove of the record, vibrations from footsteps, etc.
Under normal circumstances, the kinetic energy from the excitation is passed through to the attached mass (cartridge body and tonearm). Maybe this is what you are referring to by "damping", but that occurs outside of the cantilever. So, if you want to test the ability of the tonearm to dampen vibrations, you can do that test separately from the cantilever. That was the "tap" test that I described earlier - it was a test to see how well the tonearm could dampen vibrations. As Atmasphere stated, the Triplanar is made using vibration dampening material (I don't personally know that to be the fact, but it seems reasonable to me).
In the case of a resonance in the cantilever, kinetic energy gets trapped in the cantilever suspension and the spring vibrates in an out of control fashion. At a resonance, significant amounts of kinetic energy are transferred to the tonearm. So now you have a situation where there is a lot of energy being transferred from the stylus (which is vibrating) to the cantilever and from the mass (cartridge/tonearm), which is also vibrating. So energy is being transferred into the cantilever (spring) from both ends. When the frequency of energy transfer is just right (i.e. at the resonant frequency) this creates an unstable condition called a resonance. This is the physical mechanism by which the resonance in the cartridge cantilever operates.
A resonance that originates within the tonearm would be a different mechanism. I no reason to presume that such a resonance would, per force, trigger a resonance in the cartridge cantilever, but I would expect the cartridge to pick up the energy from this resonance. If the resonance is within the audible spectrum, I would expect that you would be able to hear it.
Apparently some here believe that the Triplanar has such resonant properties. I don't know; I've told you the sum total of my testing on the matter. But for my part, I'm probably at least as interested in understanding how all this stuff works together than I am seeking the "ultimate" sonic experience. When I got my turntable system, my attitude about it was to get a system that I expected would sound pretty good (it was replacing a Technics SL-BD20D turntable that I had had for a decade). While I ended up with a turntable system that sounded pretty good to me, what I did not like about the process was the large number of unknowns. There are 5 components that work together in a turntable system: the turntable, the tonearm, the cartridge, the phono stage and the tonearm cable. There seems to be a belief that some turntables work better with certain tonearms. I could never get a good explanation as to how these determinations were made other than they were the result of trial and error. I have since gained a better understanding (through my own efforts) of the relationship between the tonearm and cartridge, and between the cartridge, tonearm cable and phono stage. I engage in discussion like this because my primary interest is understanding how stuff works and to that end, I've learned quite a bit in discussions like this. In some ways, you can learn more when you disagree with a person than when you agree.
