As others have said context is everything in translation.

I don't know who this John O Donoghue is but "anam cara" is simply putting the word for soul next to the word for friend and is not, in my opinion very good Irish. Cara m'anam friend of my soul would be a better form of translation, but not a phrase I've heard in everyday use. "Caire mo chléibh" is a phrase used in a few songs I know (e.g Tá mé mo shuí) which means a bosom friend/companion. Another phrase might be cara dhílis (a faithful friend).

I've just noticed that the word cáirdiúl is very similar to cordial in English (and French). The words probably come from a common root.

Cómh-bhrón (shared sorrow) is an Irish word for sympathy, but not in the context of the word that we're talking about.