.. or is this just the MIDI engine making up sound for the particular track?
Is this the way the software is designed?
.. clarinets and saxophones sound like video games
It is likely the MIDI engine for the sounds.
A better sound source equals better sound (especially for any MIDI tracks).
That would be my best guess, as most styles do not use Reatracks for sax/clarinet .. more likely a MIDI based track and the MIDI 'engine' (VSTi) is the source issue. At least in my experience.
Good question and I think you know the source of the problem, just need to decide on a solution

There are many options
Again, the MAC forum would likely offer better help.