this is the very convinient compartment - не розумію, чому не може бути артикль The, якщо мова йде про конкретне купе. І чому не можна використати convinient?
"The" can be used here. If it isn't , use the button "Report".
"Convenient" and "comfortable" are two different things. "Convenient" is used to talk about something that is easy to get to or access. "Comfortable" is used to talk about something that is pleasant.