If an IME doesn't enter a standard hyphen-minus by default, no matter what the language is, that is basically engineering malpractice. How could anyone not know that would fail hard more often than not?
I type Japanese frequently, and hitting the dash/minus key results in "ー" instead of "-". The reason is justified too, namely in that Japanese is almost always typed monospaced so a normal "-" screws up the formatting. The same goes with numbers too, like "３" instead of "3".
I always switch to English input if I need to type in lots of numbers since converting to half-space everytime gets annoying and feeding mono-/full-spaced numbers into text fields usually leads to the program on the backend crapping the water closet.
A dash is definitely not the same as a minus. A hyphen however is so close as to cause a serious ambiguity, so much so that they call the standard character a hyphen minus. So if someone comes along and invents a minus or a hyphen that is distinct from a hyphen minus, and can't even be visually distinguished most of the time, that is not particularly helpful for general use.
People want to use Unicode for everything, when some things are really typesetting abstractions that should be avoided in general purpose computing. Groff and troff have their peculiar exceptions for historical reasons, but surely in retrospect it would have been better for a hyphen minus to render as a hyphen minus rather than as a hyphen.
As far as Japanese goes, the keyboard mapping there is unfortunate. Perhaps they should have considered using a shift key or something to shift between hyphen minus and dash. And in my view those ought to be two characters with typesetting variations, not six or seven.
