The problem seems to be in the rxvt extension.
I have taken a urxvt executable from another distribution (FatdogArm) which is v9.18 and it works correctly with Luxi, Hack fonts.
I see the following differences:
v9.22 by piCore
rxvt-unicode (urxvt) v9.22 - released: 2016-01-23
options: styles,combining,blink,iso14755,encodings=eu+vn+jp+jp-ext+kr+zh+zh-ext,fade,XIM,frills,selectionscrolling,wheel,slipwheel,cursorBlink,pointerBlank,scrollbars=plain+rxvt+NeXT+xterm
v9.18 from FatdogArm:
rxvt-unicode (urxvt) v9.18 - released: 2013-03-24
options: xft,styles,combining,blink,iso14755,encodings=eu+vn+jp+jp-ext+kr+zh+zh-ext,fade,transparent,tint,pixbuf,XIM,frills,selectionscrolling,wheel,slipwheel,cursorBlink,pointerBlank,scrollbars=plain+rxvt+NeXT+xterm
As can be seen in the piCore v9.22 options, xft does not appear. Could be that the problem?