“In 56.1% of instances the English oh is omitted in the Catalan version: these correspond to interjections expressing pleasure (2 instances), realisation of something plus no specific value (4 instances), realisation + complaint/moan (2 instances), realisation + surprise (5 instances), realisation + admiration (1 instance), realisation + annoyance (1 instance), agreement (5 instances) and a conative value (3 instances).”
The author also notes a great many of ‘oh’’s possible functions – for example it can flag : Pain, disappointment, surprise, pity, admiration, annoyance, phatic*-agreement, or phatic*-disagreement, to name but a few.
* Note for non-linguists : A phatic expression is one whose only function is to perform a social task, as opposed to conveying information. e.g. “Yo, wassup dude.” (US) or “Gawd luvva duck.”(UK).
Further interjectional research : The many meaning(s) of “Uh(m)”s