I've been doing 1-2G attempts a bit more now that I'm working on any% again. Once you've clipped through and need to jump back (move left) to the world 4 pipe, you typically need to do a frame perfect jump in order to prevent Mario from facing leftward.

If you hold left+down while making the turnaround, it forces Mario to face rightward and gives you some leeway on the jump to the left. The only issue might be that it might not be fast enough to save the frame rule if you don't jump frame perfectly. However, I believe it should work and should help slightly with consistency.

The same applies for the walljump in 8-4 by holding right+down while walljumping backwards in order to prevent an accidental walljump turnaround jump.

I don't use L+D on the turnaround for 1-2g as it kinda throws me off and has me feel like I don't have to jump frame perfectly, and as a result I'm too slow most of the time.

However, I do hold R+D while backward walljumping, it's kind of nice when you get to easily enter the pipe as soon as possible, but it gets much riskier due to the fact that you might land short and as a result not enter at all (unless you release right) But really, imagine double fast accel 8-4

I find this usually gives me an extra 1-2 frames of leway on my jump depending on subpixels.