You don't mention which operating system you're using so the results may be different.
I tested the staff style changes using Mac OS 10.7 and switched from a marimba to djembe. Both instruments were on separate midi channels but remained on the same layer of the staff. After entering notes for the marimba I then used 2 text expressions for the first measure of the new instrument. One expression for the instrument change, in this example you would need to change the midi channel. The second expression to change the percussion midi map. This is what is currently 'broken', I'll explain the problem in a moment. There are actually basic expressions included with the templates to do these changes. They would need to be edited for the individual situation.
After applying the expressions, switch to the Staff Tool and highlight the region or measures for the new instrument. Once they have been highlighted, from the Staff menu select Apply Staff Style and choose the appropriate style. The staff styles which came with the templates set the percussion layout. At this point you should now begin entering notes for the new instrument. Remember that after you're done with this instrument, you will need to enter a text expression to switch back to your original instrument or repeat the process for any additional instruments.
Now the problem that has arisen. When entering notes for the non-pitched instruments you can identify which note name is being entered. The XML files for VDL and the percussion layouts use a combination of Finale names and Custom names to complete the list of sounds available with each VDL instrument. What I'm seeing is that the Custom names appear only as 'Custom #' while the Finale names appear as the should.
The next step in testing is to see how this functions when using layers and a bank of instruments. The advantage of using a bank within Kontakt is that you may use up to 128 instruments all assigned to 1 midi channel. In this case, instead of using a text expression for a channel change it would be for a patch change. I'll also need to check on the staff style for the suspended cymbals.
I'll keep you updated on results.
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