I do wish you luck, I totally know what it feels like to wonder whats going wrong, get paranoid about every ingredient, and hope that the next thing that comes in the mail might somehow be the solution! You probably are in more need of advice from people who actually have it sorted! But, I do understand. I have completely different properties so I don't want to advise the wrong thing.

I am just wondering though, if you've only been CG for a short time then your problems, especially at the beginning, are not so likely to be build up. Often a product that causes build up will work well first and even second time. I wonder if your hair always had this capacity to tangle, just because of the length and density, and it was cones that were giving you enough slip to detangle it. I agree that lots and lots of moisture is the best thing, you might have lost the slip from the cones but not yet re moisturised enough to compensate. I still think all the advice about products/ingredients is worth doing though.

What was your hair like before (to detangle I mean) in between shampoo and conditioner? Did it tangle as much after shampoo, but your conditioners with cones made detangling quicker?

I would try to find a co wash that has a bit of slip, and also to get your hair as detangled as possible before starting (at least you can sit down for that!) maybe with some product, and wash it in sections if possible. Slide your fingers in along the scalp, disturbing the lengths as little as possible, and just let them be cleansed as the product rinses out. Sorry if that is stating the obvious, you've probably picked up skills in handling thick hair already!
UK based wavy

Mostly waves, but curls and straight bits too!
Fine to medium, high porosity, medium density, very low elasticity
Highlights damage (growing it out), seems to like protein and need lots of moisture.

Cleanse - CJDF, trying out low poos ; Co wash- Uk chemist brands, Urtekram Rose or Aloe, Hairveda Amala Cream Rinse; RO - varies, Tigi Moisture Maniac, Desert Essence Coconut ; Leave in - Keracare natural textures; Sealant - argan oil
Trying out new things, still looking.