Spanish in Joensuu

I have got to know many Spanish exchange students in Joensuu. The fact that I can speak have definitely had a lot of effect to it. Most of them have come to Finland to learn English and some of them want to learn even Finnish. I am wondering that should I speak just English to help them to learn speak better English. On the other hand I would like to continue improving my Spanish. I have had some conversations that I speak in Spanish and the other persons speaks English to me. That way both can practice to speak more fluently.