I think they have this the wrong way round. Indica is known for its relaxation effects. Couch lock isn't due to anxiety but relaxed passivity, and sativa strains tend to promote overthinking and paranoia in those (inc. myself) prone to it.

No. It depends on the person entirely and if you start digging you will find about equal distribution of people who are calmed by a sativa and people who are calmed by an indica. I personally suspect that people who feel calm from a sativa are a little ADHD and it seems to make them think better and more calmly and indicas make them much more anxious because it exacerbates and existing condition.

anecdotal, but i am certainly an individual with adhd and i personally find strains marketed as indica dominant to be far more effective for anxiety relief and just general functionality. it also may just be a random correlation, but i always recalled seeing higher levels of cbd in indica based strains when I lived in Washington and the actual levels of cbd and thc in the product was listed on the packaging. i certainly don't think this is strong evidence that such a thing is the case, in an overarching empirical sense, but i can at least say, with confidence, that for me, indica dominant is much less anxiety inducing

This kind of matches my experience - the anxiety I get is from feeling like my mind is slowing down / not totally working properly and not knowing if it will ever come back. I think I am a bit ADHD, and caffeine has a kind of calming effect on me as well, so might be worth trying a sativa blend.