This is the 11763rd most frequent Russian word.
заинтересованными
"Interested" or "concerned."
The word 'заинтересованными' is used as a predicate adjective in instrumental plural form describing the subject 'we' indicating their state of being engaged or interested in something.
Мы всегда остаемся заинтересованными в развитии компании.
We always remain interested in the development of the company.
The word 'заинтересованными' is an instrumental plural form adjecive modifying 'listeners' in a descriptive sense showing their interest.
Они были заинтересованными слушателями на конференции.
They were interested listeners at the conference.
Here 'заинтересованными' functions as an attributive adjective in instrumental plural form describing 'ещё сторонами' in the sentence showing the parties being actively concerned.