Your comment about the death record transcription, 1926, that you have posted here -
"..The lady transcribing the original record for the death certificate got a few relationship(s) section wrong, she was new and in training. Why they let her do such an old record, I'm not sure..."
Are you just speaking generally here about the transcription, or did you have reason to return to BDM about death certificate?
Can you be specific about the relationship errors please ......
Eileen Gertrude is 26 years old at marriage, 1884.......born ~ 1858
Eileen Gertrude is 75 years old at death, 1926.....born ~ 1851.
Who is the informant for this death record. Ages recorded at death can be unreliable.
The marriage certificate has St Thomas Church Vestry.  They are not married before the church altar. That would mean that one of the couple is not Catholic, and the priest would be ensure that it was recorded as such.
I think that they have given Christchurch as "usual residence" because that is their intended residence. Eileen has not been in NZ before her marriage.
BDM NZ births
1886/11634   MURRAY   Henry St Aubyn   
parents Eileen Gertrude St Aubyn / Henry   
1887/11462   MURRAY   Stella Frances Eileen
parents Eileen Gertrude St Aubyn / Henry   
1891/7257   MURRAY   Bernard Percival   
parents Eileen Gertrude St Aubyn / Henry
Henry would be named for his father, and St Aubyn for mother's family
Stella would be named for maternal grandmother, paternal grandmother and mother
Bernard is named for ........who?......Bernard sounds very Irish Catholic.....possibly a close male relative?.....brother? 
Percival might be a family name rather than given name  eg PERCEVAL, PERCIVAL etc.
When given the opportunity to perpetuate family names, Eileen does not include John, or BURKE or CHESTER.  St Aubyn is more important to Eileen than is BURKE.
Obviously, if there were more births you might see more possibilities.
WW1 AIF 
Henry St Aubyn Wainwright MURRAY applied for Commission 5 Nov 1915, Brisbane,   #9431, with father Henry as next-of-kin.  Front page has notation " Historian 1/10/41"
Have a look at the WW1 file....looks like WAINWRIGHT to me. Another name to ponder.
Why is Henry in Brisbane in 1915?
BDM QLD   marriage
916   B18566   Henry St.Aubyn   MURRAY  marr.    Ismena Nola   SINNIS
Queensland Figaro 6 May 1916
https://trove.nla.gov.au/newspaper/article/84400241?...marriage notice......
I think Eileen Gertrude BURKE might have been rather creative about her origins...and her age?