non-gender-specific occupational titles in English
If someone who farms is a farmer and someone who hunts is a hunter, why isn't someone who fishes called a "fisher" rather than a "fisherperson"?
A fair question. Their titles originally distinguished the occupation form the activity, not gender. Man (pronounced like the last syllable of the name Cartman) just means person (typically an adult). This pronunciation is still common on job titles in the UK. You would gender man with "wer" or "wif".
As to why some job titles got [verb]er, and other's got [verb]man. From what I can tell, it was mostly based on use. Like how almost everyone has drawn something so "drawer" is quite a meaningless label. Artist fills the role of an identity. Raper on the hand is unlikely to become an "ist" for obvious reasons.
For the most part I'd say it's absolutely brilliant. I did have a young woman in Stirling tell me they were irrelevant and nobody listened to them since the 90s and that the folks who did like them weren't even really Scottish because they spoke Gaelic and burnt peat - but I was there for one of their last concerts (look for "The Last Dance" in Stirling 2018) and saw the 50k+ who were there that Friday night to see them off so...
Anyway, the style varies. It's always a bit of folk with a rock edge - they've done songs with Julie Fowlis and Gary Innes (from Mànran) but their cover of "Rhythm of My Heart" takes me to years every time. It's a healthy mix of Gaelic and English - "Oran", "Edge of the World" and "The Ship" all show their North Uist and Highland roots. Their early stuff is more Gaelic and they made a return to that with one of their last tunes, "The Story" (an Uist band called Beinn Lee cover it and I'm usually sobbing before the singing starts).
I'm definitely a fan and I promote their music loudly and often
Well the same trend is found in Gaelic. Probably many years ago, you would have heard "fear" being used used instead of "neach" like fear-smàlaidh instead of neach-smàlaidh. Of course nowadays there are a lot more women in the roles that men would traditionally have.
I'm still not sure why ceòladair became neach-ciùil though. Maybe it's just for consistency in the course.