This reply should not be seen as me challenging you, Arch, as I have a lot of respect for you and how you have conducted yourself on MT over the years. I always enjoy reading your thoughts.
However, some terms can sound exotic to taekwondoin precisely because their practice is not common within taekwondo. It is what it is, not a criticism. Every martial art has its characteristics - for TKD that happens to be athletic kicking among other things, but TKD generally is NOT the art other martial artists think of when the following terms are brought up.
Most of these phrases or terms are from the practice of Chin Na, a Chinese subset of grappling and striking skills taught along side the 'normal kung fu'. Some styles such as Eagle Claw or Tiger Claw are particularly famous for these methods, and the bulk of them require gripping and striking/ripping/pulling/pressing with the hand and fingers - so a roundhouse kick would not be applicable here.
DIVIDING the MUSCLE and TENDON is manipulation with the fingers and hands in such a fashion as to misplace or tear another person's muscles and tendons. Many of these techniques don't require a lot of strength in the hands to execute, but some do and thus there are a lot of exercises done to make the fingers powerful yet tactile. An example would be tearing the tendons which allow a person to close their fist, ending a fight quickly.
MISPLACING the bone is simply moving the bones the wrong way as to cause pain and damage. A wrist lock is probably the common example of this. Chin Na experts however know A LOT of weird ways to grip the various parts of the body to provide the unique leverage to break joints - even when they are in standing position without the added torque from having forced someone else prone to the ground.
Balance misplacement is not one of the main inquiry lines of Chin Na, but from my studies in aikido and judo, I obviously think it's important. The basic principle of forcing or tricking a foe to break up his head/shoulder/hip/feet alignment is obvious to anyone who has practiced more than a few years, but there is a vast practice of the assorted ways to accomplish that. I guess whacking someone in the head with a roundhouse kick might be one way of doing it - perhaps even a good one - but by and large I don't know that TKD has a comprehensive way of teaching the subject outside of hit, hit, and hit again.
Cavity pressing is an advanced body of knowledge most commonly found in Chinese martial arts. It is considered master level knowledge and honestly I doubt many still know it today. And those that do don't talk about it much. It is not exactly the same thing as the pressure point striking, something that many taekwondoin know a little bit about (usually knowledge of where to block an attacker's arm to numb it). It is that and more. An adept of cavity pressing understands Eastern medicine and he can disrupt another person's blood and electrical flow (chi?) with judicious strikes at the pressure points, meridians, and organ points. The end result can be mere temporary loss of fighting capacity in a certain limb or it can be more - total disruption, even leading to a stroke and death. This likewise requires more accuracy than an instep roundhouse kick can deliver.
As for sealing the breath...well you win on that one. It's essentially keeping someone from breathing by disrupting the function of their windpipe, their lungs, the stomach muscles, or in specialized cases the vital points that involuntarily cause the lungs/stomach muscles to contract. A good hard RH kick can do the job placed judiciously even if it is not an elegant solution.
Not exactly. Hard body conditioning, at least in my experience, refers to the specific buildup of muscle, bone, and 'inner strength' to protect ones vital areas and create striking weapons with one's limbs. Most here are probably somewhat familiar with the arm and leg banging exercises to build up bone strength and density. I imagine a much smaller number have practiced something like sanchin kata or iron vest exercises or snake arm exercises to build up resistance to damage in the neck, torso, and arms and shoulders. It's much more rarified territory even outside of Korean martial arts.
We all do a few basic things, like a couple of wrist locks and a shoulder throw and a hip throw. Few do more. How many TKD dojang teach all of Funakoshi, Gichin's 9 throws of Shotokan? How many really teach chokes in an appreciable way considering the general age group of the students? I think it's fair to say this is not a strong area for TKD overall. On the other hand, TKD people usually are very good sparrers.
To be frank, I don't think Kong Soo Do is necessarily being dismissive of TKD in discussing these shortcomings. I personally don't think these things were taught to any great extent within Shotokan karate either, so unless some of the pioneers blended in a heavy dosage of Chinese martial arts along the way, there would be no reason to expect TKD to have such things.