Esen

The closed-door part is a different behaviour and worth separating, because it generalises.

What cats object to is not the room, it is the barrier and the loss of information. A cat that has never once entered your study will still complain at the study door if it is closed, and lose interest the moment it is opened, often without going in. The interest is in access, not the destination.

So the bathroom gets a double dose: it is the room she wants to be in and it is the room where the door actually gets shut. Every other room is open, so the behaviour never appears there and you never notice it.

A cheap test if you are curious: shut a different door for a week. Most people find the complaining follows the door rather than staying with the bathroom.

The second cause, and it is the one that produces the dusty result when you add more spice: the spices were never cooked properly.

Ground spices need to spend time in hot fat. That step: blooming, is where the aroma compounds are released and dissolve into the oil, which then carries them through the whole dish. Spices added to liquid, or added late, stay as suspended powder. They taste dusty because they literally are dust.

So when a recipe says fry the paste until the oil separates, that instruction is doing real work, and the time it takes is usually longer than people give it: often eight to ten minutes rather than two. Adding more spice to a dish where the first lot was never bloomed makes it dustier, not stronger, which matches what you found.

If you want to test which problem you have: take a spoonful of the flat curry, add a squeeze of lemon, taste. If it comes alive, it was acid. If it stays dull and powdery, it was the blooming.

"Deliberately destroyed, by you, on every step" makes it obvious in a way twenty years of half-answers did not. I was looking for a store and it is a brake.

For question 2, both meanings come from the same root and English simply kept different halves on each side of the Atlantic.

The word goes back through French to something meaning twice-cooked, bread baked and then dried out so it would keep. That is the hard, dry, long-lasting thing, and it is why ship's biscuit and dog biscuit and the tea biscuit all sit in that sense: they are all descendants of "dried out so it lasts".

British English kept that thread and it drifted toward small sweet baked goods. American English attached the word to a soft quick bread instead, largely through the southern baking tradition, and the older hard sense survives in American English only in fossils - dog biscuit, sea biscuit.

So neither is a corruption of the other. Both are surviving branches, and the sweet British tea biscuit is arguably further from the original meaning than the American one.