As for 'Delete' end 'End' - I think the inconsitencies are due to the fact that a) Acorn labelled these keys 'Delete' and 'Copy' in the old days and they worked completely different from the 'standard' keyboard nowadays on non-RISC OS-systems. The Acorn Delete key operated the same as the backspace delete key which was more and more frustrating if you work with different systems and a waste anyhow. The Acorn Copy key was not meant as the opposote to Pos1 but for use for some copying mechanism in CLI (which I never understood and thanks to LineEditor don't need anyhow).
As time passed by patches, tools, ... came up which modified this so that the Delete and the End (aka Copy) keys did what you'd expect them to do: Delete deletes the char to the right of the cuser (backspace deletes backwards) and End does the opposite jump to what Pos1 does (be it start/end of file, of line, ...).
In Select this issue was addressed which is good to start with but certainly was irritating for the odd user (like me) since the module I had loaded to take care of this plus the Select control didn't quite work together but that was not hard to sort out.
I'm not absoultely sure about the IYONIX pc anymore since after some initial fight with just these keys things now work as I want them to as for these keys - but I do load !PCKeys in !Boot.Choices.Boot.Tasks so I guess RISC OS 5 is Acorn-compliant as is any other RISC OS apart form Select (if so configured).
So as for these inconsistencies: You can fix that since the default is AFAIK still the strange Acorn type Delete and End (aka Copy).