"Ĉiaj boteloj povas enhavi akvon."
Translation:All kinds of bottles can contain water.
Not when the bottle's made of pure sodium.
Or a bottle made out of any water-soluble substance.
Inversely, if the water is made using tritium, and the bottle is very thin, the radioactivity may break any kind of bottle.
Smashed bottles and broken bottles can't.
If a bottle is so smashed apart that it contain any water for any amount of time, I don't think it can be considered a bottle any longer.
This sounds like a bad excuse for when your parents find a handle of vodka under your bed.
Boteloj de Klein ne povas.
Ho, tiuj glasaĵoj ne estas boteloj de Klein. Boteloj de Klein estas kvardimensiaj.
Is "All bottles can contain water" ok?
That would be more "Ĉiuj boteloj".
I responded "All kinds of bottles could contain water" and got rejected. Is that a meaningful difference?
Your sentence is either past tense ("they could yesterday but not anymore today") or conditional ("they could but only if some condition were fulfilled").
I'd say that's different from a clear positive statement that the bottles can (right now, definitely) contain water.