In my defence I did say "partly my fault".
Actually such a mistake is only possible in the TiltPi client because it takes comma-delimited lists as input for calibration. And you need to figure out calibration requires delimited lists 'cos no official document tells you this. Reading posts like this is where you find stuff like that.
And … my post was really a "public information" post for another reason; I bet there are misguided people who read this thinking "that's wrong, my Tilt measures 0.1C increments, not 0.5C". I think I was one of them for a while.
BTW My pycnometer bottle (25ml) arrived yesterday. I think I'll start a new thread for that once I've got it calibrated. 25ml requires a fairly reliable scales that can measure grams to 2 decimal digits. The little eBay ones we might use for water treatment salts, for about £10, are not up to the job (they fall over on "repeatability" returning different values weighing the same item), the bigger items (x2 or 3 the price) that the "vaping mob" use seem okay (I got one) otherwise use a bigger pycnometer bottle. The olden day guys used to weigh entire casks!