Is this the Masterson/Loftus family you have?
1901
http://www.census.nationalarchives.ie/pages/1901/Mayo/Corraun_Achill/Tonregee__East/1603415/
1911
http://www.census.nationalarchives.ie/pages/1911/Mayo/Corraun/Tonregee__East/745035/
The birth of that Catherine
https://civilrecords.irishgenealogy.ie/churchrecords/images/birth_returns/births_1893/02301/1862927.pdf
However her father is a Shoemaker (and farmer in the census) but Catherine’s father, Patrick on her marriage is a Labourer.
Also, similar to Maiden Stone with regard to work, my mother in law, raised close to Achill, was in service in Cloonfad, Roscommon in the 1920s.
He is described as a shoemaker on his death in 1923
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1923/05043/4380126.pdf
And Ellen is described as a Farmer’s wife on her death in 1935
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1935/04828/4301159.pdf
Shoemaking + farming seem to have been Patrick's consistent occupations. Shoemaking was a skill. He probably learned young. Being a farmer was a settled occupation. Income from shoemaking would have supplemented that from the farm. It doesn't sit right with me that a man who was a farmer and had a skill would temporarily switch to being a labourer in old age and that his daughter would put labourer as his occupation when she married. In my experience of family history research, people were more likely to increase the status of their fathers on marriage certificates, not minimise it.
Speaking personally, an ancestor was a shoemaker (cordwainer on his marriage certificate, a skilled maker of good quality footwear). I'm a daughter, granddaughter, great-granddaughter &c of farmers. Being a farmer and landholder had a status, no matter how small the farm or how poor the family. They may have been labourers as young men (the Irish ones working in England) but once they'd taken over farms they were farmers or landholders, even if they had to supplement their income with other work. Struggles for occupation and ownership of land in Ireland were crucial in Irish history. If I'd been Catherine, I would have said my dad was a farmer or a shoemaker, even if he was temporarily working as a labourer. *
Looking again at census returns for household of Patrick Masterson, shoemaker, I noticed that, in the read & write column, 7 year-old Catherine could read on 1901 census but 18 year-old Catherine on 1911 census couldn't read or write.
Her 14 year-old sister was a scholar in 1911. Most children would have left school by that age. I wonder what she did in later life?
Do you think that Brian, informant of Ellen's death in 1935, was Bernard on 1901 & 1911 census?
If Catherine's father was a labourer, he may have travelled to get work.
*Added. "Labourer" for Catherine's father's occupation may have been a clerical error. Michael's father was a labourer.