About pins which look more or less like Clan Crest cap badges worn as kilt pins, it's interesting to note that none of the kilt pins which appear in The Highlanders of Scotland are anything like our 20th century tall slender vertically oriented kilt pins.

Rather, the pins which appear there are circular, oval, etc.

Only 6 of the 56 kilted men have visible kilt pins:
2 plain open circles
1 plain open oval
1 clan crest style circular badge
1 crest but lacking the surrounding circle
1 complex design

So wearing a Clan Crest circular pin as a kilt pin would have been quite in style then. Today it's slightly unusual.

One of the world's top pipe bands wear large cap badges both on their caps and as kilt pins.