Monospace fonts should have (support) double-width-chars, i.e. characters 2 characters broad, therefore square. This means also most east-asian glyphs. You won't be able to distinguish Chinese symbols if you squeeze them into a 1:2 shape.Those characters count for two in length, occupying the space of two characters. Therefore a monospace font file should support double-width chars.
Dunno whether Geany supports Unicode/UTF-8. You can't use it smoothly anyway. On that front, FreeBASIC lags far behind.