I know that there are prisons where the interaction isn’t face to face, rather via phone where the only thing separating both inmate and visitor is a window (from that type of interaction, the conversation is definitely recorded but can languages alone hide the nature of the conversation?) That depends on the language spoken and it’s similarities to English (like Spanish) while languages that are very different (like Japanese or Korean) making it hard to translate.
I mean, most languages can be translated but the nuances from the mother tongue won’t be 100% retained since changes can be made plus different languages have their own cultures attached to them. As in what is considered profanity and offensive in the mother tongue translates as a normal word in English (unless you clarify the context), as in what is 100% accurate won’t be to the other party since languages are different the same way cultures are.
In my country, no.
if you are allowed to have conjugal visits - a privilege that has to be earned through time and effort - you have been deemed trustworthy enough to be left alone in a room without surveillance.
if you are not yet eligible for conjugal visits, then all your visits and phone call - although not letters for some reason - are monitored by somebody that understands your language. We use either our own personnel or contract it out to actual interpretors. If there is nobody available to translate, you are denied having the visit or phone call.