The site I researched came through the Irish Family History Foundation. It is firstname.lastname@example.org. It SHOULD have a database which contains rcds identical to those held by the various churches and civil authorities. There are no notes on omissions from the database listed in the "sources" pulldown.
The McGuirl surname appears to be confined to the Leitrim area. I suggest you browse this database.
The Mormons scoured Irish, English, Scotch, et al parish rcds from the 1950s through 1980s. They made microfilm copies of everything. The LDS practiced "baptising" ancestors by proxy as Mormons. People of other faiths thought this was blasphemy and heresy. I believe the LDS ceased this practice after non-Mormons filed and won a civil suit against them.
In many cases, these LDS microfilms are now the "best available" rcds as the "paper" rcds are becoming fragile and unreadable.