We believe that your issue has been closed by the upload of
Version 0.7.15 of grml-autoconfig from Michael Prokop <mika@grml.org>.
The explanation is attached below

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Format: 1.7
Date: Wed,  5 Sep 2007 19:09:58 +0200
Source: grml-autoconfig
Binary: grml-autoconfig
Architecture: source all
Version: 0.7.15
Distribution: unstable
Urgency: low
Maintainer: Michael Prokop <mika@grml.org>
Changed-By: Michael Prokop <mika@grml.org>
Description: 
 grml-autoconfig - main bootup process of a grml system
Changes: 
 grml-autoconfig (0.7.15) unstable; urgency=low
 .
   * config_language(): check for existence of /etc/sysconfig/keyboard
     [Closes: issue272]
Files: 
 fdb76666d7bd8b23c53bf060bcd8e16c 513 grml optional grml-autoconfig_0.7.15.dsc
 504fe0a8134017aeeb8549b512ef62d7 52550 grml optional grml-autoconfig_0.7.15.tar.gz
 8bdbc467bb11f95432a383fe86318784 53062 grml optional grml-autoconfig_0.7.15_all.deb

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When using 'jp' in grml-setkeyboard you get 'us' keyboard layout.
Thanks for reporting, manveru.