Joomla 3 component - multilanguage issue

We need joomla php expert. We are using joomla 3 cms with component with name KOPARENT. This is component for booking ([login to view URL]). We have installed system with many ADVERT SPECIFIC FIELDS and per developer we can simple translate this fields and in system when you add new field you got the name for the translation file like: fore example field name is: Location in place (in translation file: COM_KOPARENT_AC_Location_in_place="" No) - this writes bellow. We have add all fields for the english version + values and now we need to have translation of this added english fields on croatian, german and italian (we have have all fields in table ready to be added). Two things to be done: 1. find and add this advert specific fields translation on croatian, german and italian langue with the values 2. The issue as well with lanuage - eather the component is multilanguage we need to have simple solution that is user friendly for each advert title + description field so that we can add on all 4 language translations + description but that is shown only for this language.