The character width of MINUS SIGN (U+2212) is full-width.

[iwkjosec]

+0 // PLUS SIGN (U+002B)
-0 // HYPHEN-MINUS (U+002D)
−0 // MINUS SIGN (U+2212)

[hatchzo]

This is expected. Source Han Code JP is designed for use in Japanese environments, and generally, Japanese fonts assign a full-width minus sign to U+2212.

[iwkjosec]

Even in a Japanese environment, it is troublesome that the widths of plus and minus characters are different.

generally, Japanese fonts assign a full-width minus sign to U+2212.

MINUS SIGN (U+2212) and FULLWIDTH HYPHEN-MINUS (U+FF0D) are different characters.

+0 // PLUS SIGN (U+002B)
-0 // HYPHEN-MINUS (U+002D)
−0 // MINUS SIGN (U+2212)
－0 // FULLWIDTH HYPHEN-MINUS (U+FF0D)

[hatchzo]

For some glyphs, opinions on how to handle them may differ depending on the main language. While I won't discuss that here, I do think your point is valid, and I will keep it in mind for future revisions.