That's interesting. I've never had any problems with #2, and my abdominals aren't in in great shape-- I've never been able to do an unassisted sit-up. Even when I was a kid, I needed to put my feet under something.
The fourth Tibetan is the big challenge for me-- my chest and shoulders are very tight, and it took me a while to even realize that was the problem rather than the universe being out to get me. I've managed one rep of #4 that felt right-- like a coherent stretch across the front of my body.
One of the good things about T5T was realizing that I didn't have all the possible problems with the Tibetans. Another was one of the warm-ups (hands behind head, circle upper body) which improved my awareness enough that I could realize I was pulling against tightness in #4 rather than just having unspecified difficulty.
Some of the material about breathing in that book gave me some sense (no doubt incomplete) of how much I hold my breath.
I was going to start the second paragraph with '#4', and that paragraph appeared in large boldface. Markdown, stop helping so much!
An exercise:
Name something that you do not do but should/wish you did/are told you ought, or that you do less than is normally recommended. (For instance, "exercise" or "eat vegetables".)
Make an exhaustive list of your sufficient conditions for avoiding this thing. (If you suspect that your list may be non-exhaustive, mention that in your comment.)
Precommit that: If someone comes up with a way to do the thing which doesn't have any of your listed problems, you will at least try it. It counts if you come up with this response yourself upon making your list.
(Based on: Is That Your True Rejection?)
Edit to add: Kindly stick to the spirit of the exercise; if you have no advice in line with the exercise, this is not the place to offer it. Do not drift into confrontational or abusive demands that people adjust their restrictions to suit your cached suggestion, and do not offer unsolicited other-optimizing.
To alleviate crowding, Armok_GoB has created a second thread for this challenge.