I have tiberium tuned to not spread infinitely, yet it does
I have tiberium saturation set to 50%, yet it will ALL go blue
I have richness turned up, yet it's ignoring it
I have recipe value turned up, yet it ignores that too
I have the starter tiberium patch turned off, but it still generates anyway

About the only settings it seems to respect are Easy Mode, the Burner Tier items enabler, and pollution multiplier.'
It also seems to have an issue where sonic fences do not stop the spread of tiberium at all, forcing you to resort to emitter towers

I have tiberium tuned to not spread infinitely, yet it does

The setting for that does not stop trees from being turned into nodes. Is it eating trees?

I have tiberium saturation set to 50%, yet it will ALL go blue

It is a global setting that includes all tiberium, including "hidden" tiberium that you can't see. Factorio generates chunks outside of what you've explored, and simulates them. Not only that, but full saturation doesn't stop the transformation, just makes it slower.

I have richness turned up, yet it's ignoring it

How so? All that setting changes is the max a tile can have.

I have recipe value turned up, yet it ignores that too

How so? All that setting changes is how much you get from the ore.

I have the starter tiberium patch turned off, but it still generates anyway

Define "Starter patch". It can generate fairly close to the starting position, regardless of that setting. What that setting controls is a forced-gen of at least one node near the other starting ore patches.

It also seems to have an issue where sonic fences do not stop the spread of tiberium at all, forcing you to resort to emitter towers

Are they not generating the fence between 2 posts?

Tiberium was as far from any tree as it could be, it proceeds to spread slowly, seemingly forever? I've never observed it stopping its growth, even dozens of irl-days into a save when left undisturbed

at 10 and 50 for the richness setting, tiberium tiles cap out at the same number, or seem to

that forced gen node is the problem one, as with the setting off I have never NOT had a tiberium patch of at least 3 nodes dead-center of my starting resource patches. SE is installed if that matters? I do have it's extra ore option also off so I doubt it's that

fences are active and powered, no gaps, yet I can just watch the tiberium grow right through the fence.

The excessive amount of blue was a bug that was fixed for 1.1.28
The Tiberium in the starting area is indeed SE overwriting our settings, but I have this fixed for 1.1.29

The other issues you mentioned I have not been able to replicate:
If you set spread to 0, you get 20 radius patches that never spawn new nodes
If you raise the richness mod setting, the ore begins to grow above the old cap and towards the new cap
Recipe value only scales the recipes at the start of refinement chains so certain recipe loops don't create infinite resources
Powered SRF emitters and walls block Tiberium growth, so I'd be interested to see your save where they weren't working