By the way, my surname derives from the greatest and most ancient of all [proto]Celtic deities, Lug.
Variations and derivatives of his name can found ALL over Europe, from the Rus steppes, all of the UK, Spain, France, Italy, even unto modern London which was, in the begining called Lugdunum, or “fortress of Lug”.
My fraternal grandmother’s name derives from Surtr, the Norse warrior of Ragnarok.
[and on my mother’s side, her mother’s name derives from “Thor” and her father was of clan MacBeth so Google that]
“Sassenach”, my royal ass.
It’s in your genes ~ and can’t be helped.
I think you need to begin reading these names as "sentences".
We start with the honorific prefixes ~ Mac, Mc, O' and Bo ~ I think there are others but I couldn't find any clear cut references to them since so terribly many Gaelic variations have gone extinct and entirely too many Sassanach barbarians have tried to mis-spell Gaelic names with too many "ough", "wh" and "hw"s. Second, you have tribal affiliation ~ and that is usually going to have a foreshortened abbreviation that might even have started as a sentence describing the range (for cattle herding) of that particular bunch. Then, you have an "l" sound in there which may be combined with some other sound to identify a lord or noble with a specific territory he rules. Car or Ker(Kel) or Kerr (Kell) may precede any of the honorifics to denote anything from a "point", "cove", "bay", "swamp", "county", "kingdom". Some of the very long Cornish titles still appear in spain and they are full blown sentences.
Once you know the system you suddenly realize that the appearance of the same name in two places, or a hundred, in different countries, probably doesn't mean anything more than that you had a bunch of Gaelic speakers who used the same system of nomenclature, and roughly the same language. Nobody needed to relocate at all.
You find Wallace in Wales, you find Wallace in Scotland (Alba) or in Brittany or in Galicia, it's just the same doggone sentence that tells you something about some Gauls in a country, nominative singular. Spelling was optional ~ and still is!
Even the quite common and ordinary name ALEXANDER is obviously related to Wallace, as is McAlexander. The difference has to do with local dialects, anomalous spelling conventions, and misread records. I think William Alexander, Lord Stirling tells us an awful lot about the system. He's got his tribal affiliations, his place in the sequence of the generations, as well as a title to a claim of a place in Parliament all tied up in his name.
Some French nobles way back when had as many as 30+ different titles. In an attempt to nail down the family the Bourbon clan before they became kings, tied the reference to the wine country where they owned so terribly many vineyards, Beaujolais, to your position in the family. They had Monsieur (first son), Orleans (second son), Beaujolais (third son), and eldest sister was also known as "Beaujolais" and usually also named "jeanne". The "beau" is definitely tied into the now extinct Gaelic title system once present in Beaujolais ~ after the vinyards had been re-established by Gaelic speaking immigrants from Brittany (and earlier Great Britain) sometime in the 7th century. They also have the same King Ad (arthur) tales as the Welsh, with many of those stories having a clear origin in areas North of the Black Sea.
Now, regarding the Gaelic speaking people in what is now Turkey, at the time they relocated from Europe to Asia Minor, the Turks still lived nearer Tibet and China than they did Europe or Asia Minor.
We still need to deal with those pesky Galatians ~ they took over a big chunk of Asian Minor as a RULING CLASS in the 3rd Century BC.
The earlier Gauls who worked their way around to Spain had departed the Danube in the 8th Century BC.
That's half a millenium! Different folks, different period of time, and probably had difficulty communicating with each other by that time.
What was going on were a series of constant, chronic disruptions in the Balkans for about 2,000 years beginning about 1800 BC and lasting until the beginning of the withdrawl of Rome from the region about 200 AD. Some of it was due to the Iron age, other parts involved new technology in farming or raising cattle. Yet other problems arose out of wars with what many people believe were tributary tribes we now refer to as Germanic.
For whatever reason they got pushed out of the East and went as far West as they could and did quite well. Now they rule America!
And that ain't bad.