So I think it would be mispronounced and misspelt in USA.
I love
Kerstin in Sweden, it is sweet and olf-fashioned. But in USA,
Kirsten or
Kristen might be easier.
I would use a longer name as mn.
Kerstin Elisabeth,
Kerstin Maria,
Kerstin Magdalena,
Kerstin Linnea.
I would pronounce
Micah as "My-kah" in USA and other English speaking countries and as "Mee-kah" everywhere else.