About the "pre-tax" and "post-tax" terminology, you are right, I should change "post-tax" to refer to when distributions are tax-free. I had to keep the table to a certain width, so had to come up with short terminology.
I think calling an HSA "a pre-tax account that is only allowed to spend money on healthcare related items" is fair, because that's how the government refers to it. https://www.treasury.gov/resource-center/faqs/Taxes/Pages/He... "Health Savings Accounts (HSAs) were created in 2003 so that individuals covered by high-deductible health plans could receive tax-preferred treatment of money saved for medical expenses". The rest of your point on HSAs stand though.
IRA - "with an income of $140k, one cannot make ANY contribution, at least directly." Yes, this was a typo, meant it specifically only for Roth.
"One feature not many understand is that at any age, you can convert money from Trad. IRA to Roth, pay the tax" I briefly mention this in the post, but left out details for brevity sake.
"So if you can afford to pay the tax now and wait five years, you can get some or all of your money out of your IRA at any age without penalty." I do not think this is correct in the normal case. You must be 59.5 years of age unless you qualify for an exception. Also, you wouldn't want to take this money out early anyway unless you direly needed to.
For your 529 point, I only hinted at this and could've worded it better, but switching beneficiaries and the $70k limit is relevant if you have a 529 for an unborn child that you are accumulating. I'll reword this.