I am using normal, every-day english, of the variety that most people in this section of the forum converse in. I apologise - your posts led me to suspect that english was not your primary language. If I'm mistaken, I do apologise for making that suggestion.
If it isn't a language barrier issue, and you still cannot understand that "the target's AC cannot be lower than 16" is not at all synonymous with "sets the target's base AC to 16", that these are two very different phrases, with very different meanings, and that one is not interchangeable with the other, then I'm not sure I can help you reach any better understanding. They aren't the same phrases, and they don't have the same meaning as one another. The spell ensures that your AC "cannot be lower than 16". It does not "set your base AC to 16". These are two different things; the spell does one of them. It does not do the other. They are different. Other spells do "Set your base AC" - Mage armour is one such spell, as its text clearly states. Barkskin is not. They are different effects. If you are not open to contemplating the possibility that your original interpretation might be in error, then, as you say, that's pretty sad.
Right now, it seems that the spell is working exactly as 5e phb core rules dictate - but that the tooltip that describes how you get to that AC number is often in error, and needs to be fixed - on that at least, it seems we can agree.
