I was going to steer clear of this one as it appeared to be reaching a
conclusion. Another thought, though:
I am happy to be corrected, but as I undertand it, the difference between
the hard and soft sounds are to do with academic affectations of the
C19th and C20th and reflect the Greek and Latin origins of the word,
possibly being influenced by French pronunciation as well. The softer
sound was used in the last century, to be replaced by the hard in this.
As Glasgow Celtic were formed in the 1880s, the pronunciation of their
name as "Seltic" is directly descended from the prevailing trend of the
time in the best ways of oral tradition. The distinction which has arisen
is socially very useful in Scotland as people are in no doubt as to who
or what you are talking about if you use a soft 'C'.
I hope this helps,
All the best,
[log in to unmask]