Hi Alexander,
I done a search for any Crawford marriages (Kilmuir N/U) 1822 - 1854 - none
I've done a search for any births for Crawford (Kilmuir N/U) 1821 - 1854 - none.
I don't know enough about N/Uist so not sure of the other Parish records as I only have Kilmuir.
Was it merely the census info. which gave you the idea that Archibald (son of Kate Cameron) was born N/Uist?
I have searched for a marriage with surnames female MacPhail & male Crawford on SP 1848 - 1854 & there are 4. I used MacPhail 1st with soundex but didn't put in any forenames.
There are 41 deaths for surname Crawford with other names Cameron without a forename as it could have been registered anything from Catherine/Catharine/Kate/Katie/Katy/Kitty.
So there will be plenty for less than 50p which are not similar names so that will narrow things down as you will know whether Kate Cameron's hubby Archie predeceased her or not & give a possible place of death to search for him?
Looking like a trip to the mainland as N/Uist doesn't seem to be the homeland

I forgot to mention that it may be a possibility that Archie (Shoemaker) & Kate emigrated?
Anne Marie