What’s the difference between strong , robust and powerful?
For starters, this might help:
Strong is used, generally, to describe physical strength, boldness in colour, flavour or smell.
Robust would be used to describe something solid and dependable.
Powerful is more used in a kind of abstract sense such as someone or something having influence above that of the norm (A powerful leader…), but is also interchangeable with “strong” when describing colour, flavour or smell.
The word “powerful”, with its three syllables, has more imagined impact than the word “strong”.
I hope that helps!
With any beverage, having more of the base ingredient (caffeine, flavourings etc) would be described as strong or stronger than what is considered normal or average.
A coffee shot, for example, would be less diluted with milk or water (as you correctly said, “concentrated”), than a latte or cappucino, so therefore would be considered stronger (strength of flavour, and sometimes depth of colour).
You would be safe to say that coffee is too strong or too weak, but saying “too bold” or “too mild”, while understandable by an English speaker, would probably sound a bit odd.