I have done an extensive search on the web for an answer to this question.
Apart from very technical articles dealing with Unicode that are almost completely inpenetrable there is not a lot to find.
So, going back to Lightroom itself it is very clear that consecutive numeric characters in keywords are interpreted by Lightroom as a number and not as two consecutive Unicode characters that happen to be numeric characters.
Thus, B77 is interpreted as B-77 and B733 is interpreted as B-733.
Therefore as numbers 77 < 733 and so 77 precedes 733 in keyword order.
The B in front of the numeric characters does not change the observed behaviour.
I am not sure if this behaviour is a default of Unicode itself, default behaviour in SQLite, or behaviour specifically programmed into SQLite by the Adobe Lightroom engineers.
I have not found any information on the web that appears to answer this question but I also readily admit that I know next-to-nothing about SQL datadase programming and as previously stated the technical information about Unicode that I uncovered may as well have been in Mandarin for all the enlightenment it gave me.
One individual, that I am aware of, who may have some insight on this issue that frequents LuLa forums is John Beadsworth.