On SRAM/Avid brake bleeds it's not normal to have fluid come out when disconnecting the caliper syringe beyond about what you'd expect the bleed screw to displace, or some drops in other words.
When you're doing that, is the lever syringe clamped still clamped shut? (It should be.)
Does each syringe connector have an o-ring and each bleed screw have an o-ring? If any are missing at any point, that's a way air can be introduced.
Have you visually checked the hose for damage? Checked banjo bolt for tightness? Checked the barb/olive/nut assemblies are as they should be? Losing a ton of fluid at the caliper end when you disconnect the syringe raises the question of whether there's a leak somewhere.
When you do the step where you push the caliper syringe while you hold the lever syringe upright, are you applying gentle downwards pressure on the lever syringe plunger, and being sensitive that it is indeed moving up in correspondence with the pressure you're applying at the caliper? If the lever syringe wasn't moving freely during that step, the fluid could get pressurized and maybe spill out that way. Sometimes syringes can get sticky and you can fix it by taking the plunger out and lubricating their seals with brake fluid.
There aren't really any differences between the front and rear procedures. With SRAM brakes it's not supposed to make a difference how the ends of the system are positioned (unlike some systems where you want the lever to be the highest point and the caliper drain plug to be the lowest.)
Doing the actual air bleeding steps, where you push the plunger hard then pull up to coax out air, is a bit of a skill that takes practice. Importantly, you have to get a sense for when you're not seeing anything further because you've actually gotten all the air out versus because you haven't tried hard enough. It's a good idea to tap all throughout the caliper and lever with the back of a screwdriver or similar during these steps, to loosen any pockets of air that might be present.
