For Mary Walsh B 1882 +/- 5 yrs, Mountmellick RC parish, with a father forenamed William, I found 0 rcds. There is a record for this name in 1885, Mountmellick, but the father's forename is not recorded.
For William Walsh M 1877 +/- 5 yrs, I found 1 rcd, 1878.
For Mary Cooke M ditto, I found NO M rcds prior to 1892.
The search for William & Mary's M rcds infers: 1) the rcds didn't survive. 2) the rcds haven't been transcribed. 3) they married elsewhere. or 4) some of your info is incorrect.