And given that the act of making good-enough coffee isn't a very difficult task (given how readily available and quickly trained "baristas" are), and how mechanical the process is already, im not sure there's anything to suggest it isn't do-able. Its more likely a matter of cost and scale
Replicating this with electrical sensors is a pretty complex task we still haven't managed to get working, after all we are not only talking about replicating the sense of taste but also the sense of smelling and how they interact with each other.
Generating a brand new style of good coffee might need the interaction though
How to calibrate a sensor for something like that on a per user basis? I don't know, but apparently it's possible because "electronic noses" do exist but are mostly used in laboratory settings, probably on account of their price.
There's also a reason why we still use pigs and dogs for work that require good smelling senses, like search&rescue or truffle foraging. Training these animals is very expensive, but it still seems to be the cheaper option compared to building "smellobots", so I doubt smelling sensor are far enough along to be put into a ton of kitchen bots at small cost.
This is not a trivial matter! Cost is entirely the reason a host of technologically-possible automation hasn't happened outside a lab.
The sun will eventually engulf the Earth rendering this argument irreelvant.
Smell, taste and poison are all matters of physical molecules and how these interact with human physiology. We already understand these to some extent. We can already build devices that can detect some of these things to some extent. We have no grounds to say it's impossible for a human-level ability of it to be engineered. (Note that lack of positive evidence against X is not the same as positive evidence for X).
Eventually automated systems ought to be able to do this better than most people can. Why couldn't there be engineered sensors that could detect such things very well?