And this right here is exactly what this thread is about, finding where that line between mundane and supernatural. So you feel that the "earthquake" like effect crosses the line of "mundane"....perfect. What other effects do you think push the line just a bit too far?
Perfect Lie - This one is borderline, but still seems mundane to me.
Beyond the Limit - This one seems okay to me as well. I might actually make it 1 round only with no exhaustion levels, but you can push longer than 1 round with a level of exhaustion for each round past the 1st. So if you want to use if for 6 rounds, you will finish with 5 levels of exhaustion.
Disintegrating Strike - This one passes the mundane mark. A shattering strike which just breaks something into pieces would be mundane, but if it's turning something into powder with a blow, it goes beyond what mundane can do and enters the realm of the supernatural. I also wouldn't let it "break" a creature into pieces. On a creature it would break bones doing more damage and imposing some sort of condition depending on the bone(s) broken.
Unstoppable Strikes - This works as mundane to me, though I agree with the other poster that immunity should be reduced to resistance and not ignored completely. Though if it's breaking a wall of force, that would go beyond natural. Not even the Tarrasque can break a wall of force.
Dispelling Blow - This one seems to go beyond the purely mundane and into the supernatural.
Absolute Defense - This one can be mundane, though I wouldn't specify "natural 1" since a lot of tables use fumble charts. Just making it a miss is sufficient.
Guardian Surge - This one is okay.
Cry of Indominance - My issues with this is personal. I don't like mundane abilities to be able to force PCs to think or feel things. I'd change it to read, "All allies within 60 feet may gain 10 Temp HP if they wish." Whether my PC feels inspired or not should be his choice.
Perfected Form - This is okay from a mundane perspective, but I think it's too strong. At high levels you're simply going to hit everything if you always have a minimum roll of 10. Perhaps 1 round per long or short rest. Or maybe on only 1 attack in a given round.
Network of Spies - I really like this one. You'd have to be somewhere that your network can reach you, but otherwise it's very good.
Seismic Slam - Already answered this one.
Cult of Personality - I strongly dislike the no save aspect of it. If you look at cult leaders, they tend to have a few dozen to a few hundred followers. Most people make their saves.

I'd give it a save DC of 10 and limit the numbers you can have to level x CHA bonus or something.
Dance of Daggers - This one seems supernatural to me unless you are doing nothing else. I don't see someone being able to actually fight in combat AND correctly perform these techniques unless there's a little bit of supernatural going on.