Of course, the primary literary and ecclesiastical language of the monastery on Inchcolm was Latin. But the indigenous linguistic history of the regions around Inchcolm presents us with a changing tapestry of cultures throughout the recorded history of the last two millennia. Broadly speaking, the two regions in question are that North of the River Forth, specifically the modern county of Fife, and that South of the river, mainly the modern region of Lothian, with its three modern counties plus that of Edinburgh. For much of that time, it is the Celtic languages of Brythonic (Old Welsh), Pictish, and Scottish Gaelic (Gàidhlig) which dominate these two regions, but the Germanic languages of Anglian (Northern Anglo-Saxon) and Scots also successively figure in their history.
What we now call the "Celtic" group of languages were first properly classified as such by the Scottish theorist, George Buchanan (1506-1582), himself a Gaelic speaker and renowned Latin scholar. Indeed, some of the more sceptical of today's scholars claim that Buchanan more-or-less fabricated the entire concept of the Celts in the first place. But since Buchanan first noted the similarities between the languages we now classify as "Celtic", two primary branches have been distinguished by modern linguists: the Brythonic and Goidelic branches. In modern terms, the Brythonic languages include Welsh (Cymraeg), Cornish (Kernewek), and Bréton (Brezhoneg). The Goidelic languages include Irish (Gaeilge), Scottish Gaelic (Gàidhlig), and Manx (Gaelg).
A similar classification to describe this split in the Celtic family of languages into two branches denotes the Goidelic branch as "q-Celtic" and the Brythonic branch as "p-Celtic". Basically, this refers to the way in which the hard "k" sounds in Goidelic languages seem to have transformed in time into the soft "p" sounds of the Brythonic languages (it is generally assumed that the q-Celtic branch is older than the p-Celtic branch). Hence, the Gaelic word for "son of" is mac, whereas the Welsh word is ap. Equally, the Gaelic for "head" is ceann, whereas the Welsh is pen. The classification of q-Celtic and p-Celtic languages were first introduced in the nineteenth century, but is still commonly used by linguists and historians to this day. In ancient history, the majority of Britain is often claimed to have spoken forms of p-Celtic or Brythonic (known in its later manifestations as Old Welsh), although the Picts of North-eastern Scotland appear to have spoken a variant of Brythonic which still eludes precise classification due to the lack of substantial literary remains in that language (although Pictish literature in Latin, such as The Book of Deer does indeed exist - they were not an illiterate culture by any means). Furthermore, the Picts were absorbed into a q-Celtic or Gaelic-speaking political hierarchy based in Western Scotland from the ninth century onwards, and this is generally described as the origins of the modern Scottish nation under the kingship of Cináed mac Alpin (Kenneth MacAlpin), who had a Gaelic father and a Pictish mother. This combination of Gaelic and Pictish cultures may go some way to explaining some of the differences between the Irish and Scottish forms of Gaelic - for example, common Northern Scottish placename elements such as strath (eg. Strathspey) and aber (eg. Aberdeen) are Brythonic, not Goidelic. In Northern cases, such elements are specifically Pictish, but both words are still current in modern Welsh as strad and aber. These placename elements are rare in Ireland, the historical heartland of the modern Goidelic languages. In many senses, the early historical languages of Southern Scotland present a simpler case, being easily identifiable as Brythonic, the forerunner of modern Welsh. Indeed, the first poem to survive in Old Welsh was actually written in Lothian by the poet Aneirin around 600 AD.
It should also be noted, however, that Scots, one of the major modern Scottish languages, is not in fact a Celtic language, but Germanic, being a close relative of English, deriving from Northern Anglo-Saxon (ie. Anglian) with seventh century roots in the Lothians. But that, as they say, is another story, and the primary cultures which influenced the placenames which Inchcolm has had involve specifically Celtic, rather than Germanic aspects.
Overall, then, the shifting pattern of languages in the regions around Inchcolm break down as follows: a Brythonic or Old Welsh-speaking culture South of the River Forth in Lothian, which changes to the Germanic languages of Anglian and then Scots from around the seventh century. North of the Forth, in Fife, we find a Pictish culture with its apparent Brythonic associations gradually being transformed into a Gaelic-speaking culture, possibly around the end of the first millennium, with Scots slowly making inroads into the region after the thirteenth century.