Yes, it is expected that the default template uses HALion Sonic SE (or short HSSE).
HSSE can also play the Symphonic Orchestra sounds and it can do it more efficiently than the HSO player, because HSSE can produce 16 different instruments at the same time. This is better than loading 16 single instances of the HSO player. It saves memory and cpu. So you should actually never use the HSO player and always use HSSE.
Now back to the other problem with the string sound. Now that we clarified that you have the HSO sounds, I don’t quite understand where the problem is. Could you please elaborate again?