I do not know if it's just me that this is happening.
I'm with the latest version of Sonar (2017.01).
I'm doing something quite simple:

1) Open a blank project, add 2 VST (for example 1 - Cakewalk TTS, 2 - Dropzone) and export all this as a track template (File -> Export -> Track Template):
 


2) Open a new blank project and insert the track template already created (Insert -> Track Template):
 

 
4) Only 1 VST is coming from the track template:
 

 
Could someone make the identical simulation to see if the same problem occurs?

tts is a dx plugin, i believe? that could be the issue

To have both synths in the template, select at least one track for each synth. I prefer to select all tracks that should go into the template. In this case, the result would be the same.

First "select all tracks that should go into the template".  
Yeah, this is a rule I did not know, thank you!
 
But now there's something else that might be a bug, I do not know:
1) Some of my tracks have to be with INPUT ECHO ON. When the template is imported they come as OFF.
2) Some original MIDI tracks must have MIDI IN pointed to a specific Soft Synth on a specific channel. For example, MIDI track 1 should have Midi In with Synth "a", channel 1 and track 2 should have Midi In with Synth "b", channel 2. This is lost when the track template is imported.
How to solve this?

I have seen and reported an issue with Echo On and instrument tracks. If a track template is created from an instrument track with Echo On enabled, the template will get inserted with the Echo On button not lit even though input echo is enabled. Moreover, the Echo On button is not functional. The only way to recover is split and recreate the instrument track.
 
I have not needed different channels in my work but would not be surprised if there were issues with it.