Once upon a time there was a terminal without a delete key. This problem has been perpetuated in Linux and is still a never ending nightmare. It has been worked around separately in all programs that have to deal with these keys and they have now ended up to be configurable and therefore are likely to come in configured wrong. And so is Konsole.
Konsole emits DEL (0x7f) for the BS key and ESC[3 for the DEL key if the `BS sends DEL' option is activated, and then behaves like a typically configured Linux console. Ctrl-H (0x08) is then left for the use of the application programs, e.g. typically configured emacs help.
When this options is not set, the BS key sends BS (0x08) and the DEL key sends DEL (0x7f), as regular VT100s and IBM PCs do.
[ Since every program can be configured BS=BS, DEL=DEL, and the poor terminal without delete key mentioned above exists today only in legends, the author wonders why this BS hack is still around. ]
ctrl-ˆ == ctrl- == ctrl-` == RS == 0x1e cannot be typed with an european keyboard map loaded, since all three base characters are prefixes (i.e. are eventually to be continued with a second character). X11 is known to have these dead keys.