If the old scores were created without VDL then the answer is no, you can't just add the maps to old scores and have it play back correctly. there are two components to the Finale templates. The first is the XML files. These assign/match names from the VDL collection to the various midi notes to which the sounds are mapped. This is so that Finale knows which sound to playback when a specific midi note is used. The second part is the percussion layouts. These take the various sounds (note names from the XML files) and place them (lay them out) on the appropriate staff and assign noteheads for the sounds. The XML files should note be edited. The sounds assigned to the different midi notes is done by the guys at Tapspace. The percussion layouts can be edited for staff placement (different lines or spaces) and notehead selection.
The simplest solution is to reenter the non-pitched percussion parts. You can copy/paste and pitched percussion. Do this after you have created a score that matches the old one as far as number of measures, time and key signatures, etc.
Let us know if you have any more questions.