The linux sparc testing package now loads OK to the stage of fonts bug 231831.
The splashscreen with debian log has been observed and the initial window and menus are displayed. I used strace and found the offending font, after moving that away it stops at another. It seems many fonts are involved. so the current status is the current bug 235763 is no longer reproducible, and sparc suffers from 231831 similar to other platforms. Regarding the segfault in upstream builds and kpackage etc, this was removed initially by killing a runaway fetchmail. The problem reoccurred and was for a short time resolved by running upstream with LD_LIBRARY_PATH=/usr/lib/debug (libc6-dbg). This later became ineffective then the condition was resolved by sleeping overnight, in the morning the problem has gone. As my platform is a mixed stable/testing it is unlikely this can be reproduced.