What specifically is the issue you are seeing when working with mallet/pitched instruments?
I presume you are using a template from TWS since you mention that the non-pitched instruments are working as expected. If you are working from the template file that allows you to create any score (not the battery only or ensemble files) than it is important to know that you will need to change the transposition setting for the glock and xylo instruments. By default, finale sets these to playback in the correct octave. When working with VDL, this is not necessary because the VDL sounds are sampled and mapped to the standard staff positions. This means no transposition is required.
Changing transpositions is done with in the Score Manager. review the Finale Help documentation or let me know if you have any questions.
Mac OS 10.12, 10.14, 10.15, Win7, Win10
VDL2.5.5, Finale 2010-14.5, Finale 25-27
Kontakt 4-6, various other soft synths