http://bugs.winehq.org/show_bug.cgi?id=32965
--- Comment #12 from Mathew sal_vager@o2.co.uk 2013-02-16 05:55:47 CST --- Okay I have tried copying one font at a time from .PlayOnLinux/wineprefix/ksp/drive_c/windows/Fonts to a new prefix to find which specific font is the one we need.
It turns out to be two of the fonts from the eufonts pack, Arial.ttf and ArialBd.ttf
Ariel.ttf alone will work but looks strange in places where KSP uses bold text.
I had tried to fix this with the POL Microsoft Core Fonts pack without success even though it includes Arial and ArialBold.
I can't see what's different between the eufonts version of Arial and the mscorefonts version, or with the version of Arial bundled with Ubuntu for that matter.
Also, Arial is what used to be the Unity and KSP default, I'm guessing when Unity4 cannot find Helvetica it will fallback to Arial if it can find it and if that file is "right".