Sources which contain useful and fascinating information on Scattery Island/Inis Cathaigh, courtesy of The National Museum of Ireland, include:
Monasticon Hibernicum which is a digital update of Archdall’s detailed archive of the monastic site as Scattery https://monasticon.celt.dias.ie/showrecord.php?id=3904 .
UCC CELT where they publish many digital versions of historical sources including the life of St Senan among other excellent resources https://celt.ucc.ie/published/T201023.html.
The Down Survey maps of the Barony of Moyfertagh, Clare show also show Scattery in the Seventeenth century http://downsurvey.tcd.ie/down-survey-maps.php#bm=Moyfertagh&c=Clare.
There are a lot more digital resources on Scattery which can be found in other places such as the Calendar of Papal Registers https://www.british-history.ac.uk/search/series/cal-papal-registers–brit-ie?query=scattery&title= where there are Papal letters which mention Scattery.
The following link shows some very interesting views and information on The Oratory, St. Senan’s Church, and The Cathedral on Scattery Island: https://www.crsbi.ac.uk/quick-search?q=scattery&WINID=1615539915006
The following is the National Monuments Map viewer https://maps.archaeology.ie/HistoricEnvironment/.